Answer:
A. 0.433 moles of HNO₃
B. 6.07×10⁻⁵ moles of NaCl
C. 3.51×10⁻³ moles of sucrose
Explanation:
Part A.
Molarity . volume = moles
1.70 mol/L . 0.255L = 0.433 moles
Part B.
1.35 m of NaCl means, a molal concentration (m). Moles of solute in 1kg of solvent.
Let's convert 1 kg to mg for the rule of three
1 kg = 1×10⁶ mg
So in 1×10⁶ mg of solvent, we have 1.35 moles of solute (NaCl)
In 45 mg, we would have ( 45 . 1.35) / 1×10⁶ = 6.07×10⁻⁵ moles of NaCl
Part C. 1.50 % by mass means, 1.50 g of solute, in 100g of solution.
Let's make a rule of three:
In 100 g of solution we have 1.50 g of sucrose
In 80 g of solution, we would have (80 . 1.50) / 100 =1.2 g of sucrose.
Then, let's convert the mass in moles ( mass / molar mass)
1.2 g / 342 g/m = 3.51×10⁻³ moles
(A) 0.433 moles of HNO₃ in 255mL of 1.70M HNO3
(B) 6.07×10⁻⁵ moles of NaCl in 45.0mg of an aqueous solution that is 1.35m NaCl
(C) 3.51×10⁻³ moles of sucrose in an aqueous solution that is 1.50% sucrose (C12H22O11) by mass
(A) 255mL of 1.70M HNO3(aq)
Molarity × volume = moles
1.70 × 0.255L = 0.433 moles of HNO3
(B) 45.0mg of an aqueous solution that is 1.35m NaCl
1.35 m of NaCl means, a molal concentration (m). Moles of solute in 1kg of solvent.
In 45 mg, the number of moles is:
45 × 1.35 / 1×10⁶ = 6.07×10⁻⁵ moles of NaCl
(C) 80.0g of an aqueous solution that is 1.50% sucrose (C12H22O11) by mass
the solute is 1.50 % by mass, that is :
1.50 g of solute, in 100g of solution.
In 80 g of solution
80 × 1.50 / 100 =1.2 g of sucrose.
Now, convert the mass in moles
number of moles = given mass / molar mass
1.2 g / 342 g/m = 3.51×10⁻³ moles of sucrose
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Compared to the atomic radius of a sodium atom, the atomic radius of a potassium atom is larger. The larger radius is primarily a result of the potassium atom having:______________.
The larger atomic radius of potassium, as compared to sodium, is due to the increase in the principal quantum number, n, as you move down a group in the periodic table. This denotes an increase in electron shells, which increases the atomic radius. A less effective nuclear charge on more distant electrons also contributes to the larger size.
Explanation:Compared to sodium, the atomic radius of a potassium atom is larger primarily because of the increase in the principal quantum number, n, which leads to larger radii. Potassium, like other elements in its group, has more electron shells than sodium, which causes its size to be larger.
As one moves down the groups in the periodic table, the number of electron shells increases. This means that the principal quantum number (n), which denotes the electron shell number (energy level), increases. As a result, the atomic radius also increases. In the case of potassium and sodium, Potassium is placed below Sodium on the periodic table, thus it has a higher principal quantum number, i.e., more electron shells, which increases the atomic radius.
This phenomenon can also be explained using the concept of effective nuclear charge. This refers to the pull exerted by the nucleus on the outermost electrons. As you move down a group, more shells of electrons are being added and hence the outermost electrons are not as strongly pulled by the nucleus, thus increasing the atomic radius.
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The molar mass of an element is the mass of one _______ of the element.
Calculate the number of moles of potassium permanganate (KMnO4) corresponding to 230.8 g of the substance.
Answer:
The answer to your question is 1.46 moles of KMnO₄
Explanation:
Data
number of moles = ?
mass = 230.8 g
molecular mass of KMnO₄ = 39 + 55 + (16 x 4) = 158 g
Process
1.- Use proportions and cross multiplication to answer this problem.
158 g of KMnO₄ ---------------- 1 mol
230.8 g of KMnO₄ ----------- x
x = (230.8 x 1) / 158
2.- Simplifying
x = 230.8 / 158
3.- Result
x = 1.46 moles
Select all of the atoms which bear lone electron pairs. gray = c; white = h; red = o; blue = n; dark green = cl; brown = br; light green = f; purple = i; yellow = s; orange = p. double click to select atoms.
Answer:
Red = O; blue = N; dark green = Cl; brown = Br; light Green = F; purple = I; yellow = S; orange = P
Explanation:
Hydrogen is in group 1 (1 A) of the periodic table and has a single electron, hence no lone pairs
Carbon belongs to group 16 (IV A) and has four electrons in its outermost shell with no lone pair.
Nitrogen and phosphorous atoms belong to group 15 (V A) and have a single lone pair in their orbital.
Oxygen and sulfur are present in group 16 (VI A) and have two lone pairs in their outermost shell.
Florine, chlorine, bromine and iodine all are halogens present in group 17 (VII A). They have three lone pairs in their outermost shell.
The atoms, which have lone electron pairs, are oxygen (O), nitrogen (N), chlorine (Cl), bromine (Br), fluorine (F), iodine (I), sulfur (S), and phosphorus (P). These elements have incomplete outer electron shells, hence they keep uninvolved electron pairs.
Explanation:In the given list of atoms, the atoms which bear lone electron pairs are the oxygen (O), nitrogen (N), chlorine (Cl), bromine (Br), fluorine (F), iodine (I), sulfur (S), and phosphorus (P). These elements bear lone electron pairs because their outer shells are not fully filled with electrons, therefore they tend to hold onto these pairs of electrons that are not involved in bonding. For example, oxygen has 6 valence electrons, 4 of which are involved in bonding and the other 2 remain as a lone pair.
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Calculate the amount of water (in grams) that must be added to (a) 5.00 g of urea (NH2)2CO in the preparation of a 16.2 percent by mass solution, and (b) 26.2 g of MgCl2 in the preparation of a 1.5 percent by mass solution.
Answer:
a. 25.8 g of water
b. 1720.4 g of water
Explanation:
A percent by mass, means the grams of solute in 100 g. of solution. So, 16.2 g of urea are contained in 100 g of solution.
Then, solute mass + solvent mass = solution mass
16.2 g of urea + solvent mass = 100 g
solvent mass = 100 g - 16.2 g → 83.8 g
Now we can make the rule of three:
16.2 g of urea use 83.8 g of water
then, 5 g of urea would use (5 . 83.8) / 16.2 = 25.8 g of water
b. 1.5 % by mass, means 1.5 g of solute in 100 g of solution.
So water mass, for this solution will be 100 g - 1.5 g = 98.5 g
Now, we apply the rule of three:
1.5 g of solute use 98.5 of water
26.2 g of solute will use (26.2 . 98.5)/1.5 = 1720.4 g
The 5.00 g of urea in the preparation of a 16.2 percent by mass solution need 25.8 gram of water and 26.2 g of magnesium Chloride in the preparation of a 1.5 percent by mass solution needs 1720.4 g of water.
Percent by mass solution, means the grams of solute in 100 g. of solution.
(A) So, 16.2 g of urea are contained in 100 g of solution.
So, 83.8 water added to make 16.2 g solution.
Thus, 5 g of urea need
[tex]\bold {\dfrac { (5\times 83.8)} { 16.2} = 25.8 g}[/tex]
(B). 1.5 % by mass, means 1.5 g of solute in 100 g of solution.
So, 98.5 g of water added to prepare 1.5 % solution.
26.2 g of Magnesium Chloride will use
[tex]\bold {\dfrac {26.2 \times 98.5}{1.5} = 1720.4 g}[/tex]
Therefore, the 5.00 g of urea in the preparation of a 16.2 percent by mass solution need 25.8 gram of water and 26.2 g of magnesium Chloride in the preparation of a 1.5 percent by mass solution needs 1720.4 g of water.
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5) Each element is unique and different from other elements because of the number of protons in the nuclei of its atoms. Which of the following indicates the number of protons in an atom's nucleus? A) atomic mass B) atomic weight C) atomic number D) mass weight E) mass number
Answer:
the answer is c
Explanation:
The number of protons within the nucleus of a given atom is equal to the atomic number of the corresponding element, which can be found on the periodic table. For example, the atomic number of helium is two. Therefore, the number of protons is also two.
Each element is unique and different from other elements because of the atomic number.
Atomic number:
It is the number of protons in an atom. The atomic number is unique for every element.
Atomic mass:
It is the sum of the protons and neutrons in an atom. The atoms with same atomic number are called isobaric.
Therefore, each element is unique and different from other elements because of the atomic number.
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The noble gases are inert. This means they a. exist as gases at room temperature. b. undergo many chemical reactions. c. lose and gain electrons easily. d. undergo very few chemical reactions.
The noble gases undergo very few chemical reactions. They are stable and unreactive due to their full valence electron shells.
Explanation:The noble gases d. undergo very few chemical reactions. The noble gases, such as helium, neon, and argon, are characterized by their high stability and low reactivity. They have full valence electron shells, which makes them unreactive and unlikely to form compounds with other elements. Because of their stable electron configurations, noble gases do not readily lose or gain electrons, meaning they do not undergo many chemical reactions.
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Noble gases are elements that are chemically very stable and undergo very few chemical reactions due to their complete outer electron shell. They do not easily give or accept electrons, thereby making them generally nonreactive. However, under extreme conditions, some noble gases like xenon can form compounds.
Explanation:The noble gases are elements in group 18 of the periodic table including helium, neon, argon, krypton, xenon, and radon. They're named 'noble' due to their unique characteristics of being largely inert, or unreactive. Their outer electron shell is completely filled, which makes them high in ionization energy and resistant to forming compounds under normal conditions. This means that they do not readily give or accept electrons - hence they are chemically very stable, or in other words, they undergo very few chemical reactions.
However, there are a few exceptions to the rule. For example, under high pressure and temperature conditions, some noble gases like xenon can be forced to create compounds such as xenon hexafluoride (XeF6).
Despite their general chemical inactivity, noble gases have various practical applications. They are used in neon signs, as inert atmospheres in certain industrial processes, and as coolants due to their low boiling and melting points compared to other substances of similar atomic or molecular masses.
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When glucose is consumed, it reacts with oxygen in the body to produce carbon dioxide, water, and energy. How many grams of carbon dioxide would be produced if 45 g of C6H12O6 completely reacted with oxygen?
Answer:
66g
Explanation:
The first step to solving this problem is by writing a balanced chemical reaction.
Here we have glucose reacting with oxygen to give carbon iv oxide and water plus energy.
C6H12O6 + 6O2 —-> 6CO2 + 6H2O + energy
From the chemical reaction, we can see that 1 mole of glucose yielded 6 moles of carbon iv oxide. This is the theoretical relation
Now, we need to get what happened actually. Firstly, we get the number of moles of glucose reacted. This can be obtained by dividing the mass by the molar mass. The molar mass of glucose is (6 * 12) + (12 * 1) + (6 * 16) = 72 + 12 + 96 = 180g/mol
The number of moles is thus 45/180 = 0.25 mole
Now we proceed to get the number of moles of CO2 produced.
Since 6 moles of CO2 were produced from one mole of glucose, the number of moles of glucose produced is thus 6 * 0.25 = 1.5 moles
Since we have the number of moles of CO2 now, we need to know the molar mass to enable us get the mass
The molar mass of CO2 is 12 + 2(16) = 44g/mol
The mass yielded is thus 1.5 * 44 = 66g
The recommended maintenance dose of aminophylline for children is 1 mg/kg/h by injection. If 10 mL of a 25-mg/mL solution of aminophylline is added to a 100-mL bottle of dextrose injection, what should be the rate of delivery, in milliliters per hour, for a 40-lb child?
Final answer:
To calculate the rate of delivery of aminophylline for a 40-lb child, convert the weight to kg and multiply by the recommended dose. Then, divide the dose by the concentration of the aminophylline solution to find the rate of delivery in mL/h.
Explanation:
To find the rate of delivery for a 40-lb child, we need to first convert the weight of the child to kilograms. Since 1 pound is equal to approximately 0.4536 kilograms, a 40-lb child would weigh 18.14 kg. The recommended maintenance dose of aminophylline for children is 1 mg/kg/h, so for a 40-lb child, the dose would be 18.14 mg/h.
To find the rate of delivery in milliliters per hour, we need to consider the concentration of the aminophylline solution. In this case, 10 mL of a 25-mg/mL solution of aminophylline is added to a 100 mL bottle of dextrose injection. This gives us a total volume of 110 mL of aminophylline solution. Since we want a rate of delivery in milliliters per hour, we divide the dose (18.14 mg/h) by the concentration (25 mg/mL) to get the volume per hour. This gives us a rate of delivery of approximately 0.74 mL/h.
How did Dalton describe the relationship between atoms and elements? An element is made up of one kind of atom. Atoms are made up of combinations of elements. Elements are made up of atoms arranged in whole-number ratios. Different kinds of atoms chemically combine to form elements.
Dalton described the relationship between atoms and elements in terms of the composition of elements and the combination of atoms to form compounds.
Explanation:Dalton described the relationship between atoms and elements in the following way:
An element is always made up of one kind of atom. Each element is composed of atoms that have the same number of protons.Atoms are made up of combinations of elements. Atoms combine with other atoms of different elements to form compounds.Elements are made up of atoms arranged in whole-number ratios. The atoms of different elements combine in fixed ratios to form compounds.Different kinds of atoms always chemically combine to form elements. Atoms of different elements can combine in various ways to form new substances.Learn more about Dalton's atomic theory here:https://brainly.com/question/13157325
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Dalton described elements as being made up of a single, unique type of atom. Atoms of different elements differ in properties. Atoms combine in fixed, whole-number ratios to form compounds.
John Dalton, the English chemist, proposed a theory that is fundamental to understanding chemical elements and atoms. According to Dalton's atomic theory:
Elements are made of extremely small particles called atoms.Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.Atoms cannot be subdivided, created, or destroyed by chemical means.Atoms of different elements combine in fixed, small, whole-number ratios to form compounds.Hence, Dalton described the relationship between atoms and elements by stating that each element is composed of one kind of atom unique to that element, which can combine to form more complex structures.
Identify the true statements about colloids.
a.) Emulsions are a type of colloid
b.) The particals of a colloid are larger than the particles of a solution
c.) The particles of a colloid will settle over time
d.) Many colloids scatter light (tyndal effect)
Answer : The true statements are:
(a) Emulsions are a type of colloid
(b) The particles of a colloid are larger than the particles of a solution
(d) Many colloids scatter light (tyndal effect)
Explanation :
Colloid : It is defined as the solution in which the one substance is insoluble in another solution that means the insoluble substance rotating in the solution.
The particles of a colloid are larger than the particles of a solution.
Colloid do not separate on standing.
Cannot be separated by filtration.
Scatter light (Tyndall effect).
For example :
Milk is considered as a colloid because various substances (fats, proteins etc..) are present in milk which are suspended in a solution.
Suspension : It is a heterogeneous mixture in which some of the particles are settle down in the mixture on standing or over time.
The particles in a suspension are far larger than those of a solution.
Emulsion : It is a mixture of two or more liquids that are normally immiscible.
Emulsions are a type of colloid.
When the equation, ___O2 + ___C 2H 6 → ___CO2 + ___H2O is balanced, the coefficient of O2 is: When the equation, ___O2 + ___C 2H 6 ___CO2 + ___H2O is balanced, the coefficient of O2 is:
Final answer:
To balance the equation C₂H₆ + O₂ → CO₂ + H₂O, we end up with a balanced chemical equation of 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O, where the coefficient of O₂ is 7.
Explanation:
The question concerns the balancing of a chemical equation involving ethane (C₂H₆) and oxygen (O₂) to produce carbon dioxide (CO₂) and water (H₂O). Balancing chemical equations requires ensuring that the number of atoms of each element is the same on both sides of the equation. Starting with the unbalanced equation C₂H₆ + O₂ → CO₂ + H₂O, we first balance the carbons (C) and hydrogens (H) by adjusting the coefficients of the products. For example, the equation can be balanced by placing a coefficient of 3 before H₂O and 2 before CO₂, resulting in C₂H₆ + O₂ → 2CO₂ + 3H₂O. However, this leads to seven oxygen atoms on the product side. We need an even number of oxygen atoms to balance them with the O₂ reactant, so we use a fractional coefficient of 3.5 (which is 7/2) in front of O₂.
To remove the fractional coefficient, we can multiply all coefficients by 2, resulting in the balanced chemical equation: . Thus, the coefficient of O₂ when the equation is balanced is 7.
What type of compound does the formula CuCl2 represent?
A) ionic salt
B) covalent molecule
Answer: A) ionic salt
Explanation: Chlorine has a high electronegativity of 3.0. Copper like most metals has a low electronegativity, So the bonding is ionic making the compound an ionic salt.
At pressures greater than 60,000 [tex]k_{Pa}[/tex], how does the volume of a real gas compare with the volume of an ideal gas under the same conditions?
A. It is much greater.
B. It is much less.
C. There is no difference.
D. It depends on the type of gas.
Answer: option A. It is much greater
Explanation:
A sample of TNT, C7H5N3O6 , has 8.94 × 1021 nitrogen atoms. How many hydrogen atoms are there in this sample of TNT?
Answer:
1.49×10²² atoms of H are contained in the sample
Explanation:
TNT → C₇H₅N₃O₆
1 mol of this has 7 moles of C, 5 moles of H, 3 moles of N and 6 moles of O
Let's determine the mass of TNT.
Molar mass is = 227 g/mol
As 1 mol has (6.02×10²³) NA atoms, how many moles are 8.94×10²¹ atoms.
8.94×10²¹ atoms / NA = 0.0148 moles
So this would be the rule of three to determine the mass of TNT
3 moles of N are in 227 g of compound
0.0148 moles of N are contained in (0.0148 .227) / 3 = 1.12 g
Now we can work with the hydrogen.
227 grams of TNT contain 5 moles of H
1.12 grams of TNT would contain (1.12 .5) / 227 = 0.0247 moles
Finally let's convert this moles to atoms:
0.0247 mol . 6.02×10²³ atoms / 1 mol = 1.49×10²² atoms
The number of Hydrogen atoms in the TNT is 1.51×10²² atoms.
We'll begin by calculating the number of mole of nitrogen that contains 8.94×10²¹ atoms of nitrogen.
From Avogadro's hypothesis,
6.02×10²³ atoms = 1 mole of N
Therefore,
8.94×10²¹ atoms = 8.94×10²¹ / 6.02×10²³
8.94×10²¹ atoms = 0.015 mole of N
Next, we shall determine the number of mole of TNT (C₇H₅N₃O₆) that contains 0.015 mole of N
3 moles of N are present in 1 mole of TNT (C₇H₅N₃O₆).
Therefore,
0.015 mole of N will be present in = 0.015 / 3 = 0.005 mole of TNT (C₇H₅N₃O₆).
Next, we shall determine the number of mole of H in 0.005 mole of TNT (C₇H₅N₃O₆).
1 mole of TNT (C₇H₅N₃O₆) contains 5 moles of H.
Therefore,
0.005 mole of TNT (C₇H₅N₃O₆) will contain = 0.005 × 5 = 0.025 mole of H
Finally, we shall determine the number of atoms in 0.025 mole of H.
From Avogadro's hypothesis,
1 mole of H = 6.02×10²³ atoms
Therefore,
0.025 mole of H = 0.025 × 6.02×10²³
0.025 mole of H = 1.51×10²² atoms.
Thus, the number of atoms of Hydrogen in the sample of the TNT is 1.51×10²² atoms.
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Methane gas is produced from the reaction of solid carbon and hydrogen gas: C(s)+2H2(g)→CH4(g) . How many liters of hydrogen gas at standard temperature and pressure (STP) are required to produce 40 liters of methane?
Answer:
80 liters
Explanation:
At STP, 1 mole of ideal gas has a volume of 22.4 liters.
Therefore, since liters and moles are directly proportional, we can use stoichiometry directly.
40L CH₄ × (2L H₂ / 1L CH₄) = 80L H₂
I’m having trouble with questions 1, 3, and 5. Can anyone help?
Answer:
i cant read sideways
Explanation:
Answer: Solution attached.
The equation are already balanced also.
Explanation:
The largest reservoir of carbon in the carbon cycle is in sedimentary rock that may take hundreds of millions of years to return to the living portion of the cycle. What is the second largest reservoir of carbon?
Answer:
The Ocean
Explanation:
The ocean is the second largest reservoir of carbon. Microbial activities carried out in deep oceans and seas leads to the release of carbon into the environment and due to low level of depletion in the lithosphere its been stored up and .
Which of the following is NOT possible? a. compressing 10 liters of oxygen gas into a 1-liter volume b. compressing 2 liters of water into a 1-liter volume c. filling a balloon using helium gas from a pressurized tank d. allowing 5 liters of compressed air to expand to a volume of 100 liters
Answer:b
Explanation:
Answer: B. Compressing 2 liters of water into a 1 liter volume.
Explanation: Liquids have little compressibility as compared to gases. Their molecules are quite near each other compared to gases which far apart. When liquids are compressed up to their capacity it will begin to resist. But gases have higher compressibility rate than liquids.
Theresa Morgan, a chemist, has a 15% hydrochloric acid solution and a 65% hydrochloric acid solution. How many liters of each should she mix to get 390.625 liters of a hydrochloric acid solution with a 49% acid concentration?
Answer:
125 L of 15% and 265.625 L of 65% HCl
Explanation:
let x = volume of 15% HCl, y = 65% HCl
15x + 65y = 49 × 390.625
15x + 65y = 19140.625
x + y = 390.625
x = 390.625 - y
substitute for x in equation 1
15 (390.625 - y) + 65y = 19140.625
5859.375 - 15 y + 65 y = 19140.625
50 y = 19140.625 - 5859.375 = 13281.25
y = 132181.25 / 50 = 265.625 L
X = 390.625 - y = 390.625 - 265.625 = 125 L
PLEASE SHOW YOUR WORK!!
6. Using the following equation: 2 NaOHH2SO4 --> 2 H2O+Na2SO4
How many grams of sodium sulfate will be formed if you start with 200 grams of sodium hydroxide and you have an excess of sulfuric acid?
7. Using the following equation: Pb(SO4)2+4 LiNO3 --> Pb(NO3)4+2 LiSO4
How many grams of lithium nitrate will be needed to make 250 grams of lithium sulfate, assuming that you have an adequate amount of lead (IV) sulfate to do the reaction?
Answer:
6. 355.1 g of Na₂SO₄ can be formed.
7. 313 g of LiNO₃ were needed
Explanation:
Excersise 6.
The reaction is: 2 NaOH + H₂SO₄ --> 2 H₂O + Na₂SO₄
2 moles of sodium hydroxide react with 1 mol of sulfuric acid to produce 2 moles of water and 1 mol of sodium sulfate.
If we were noticed that the acid is in excess, we assume the NaOH as the limiting reactant. Let's convert the mass to moles (mass / molar mass)
200 g / 40 g/mol = 5 moles.
Now we apply a rule of three with the ratio in the reaction, 2:1
2 moles of NaOH produce 1 mol of sodium sulfate.
5 moles of NaOH would produce (5 .1)/2 = 2.5 moles
Let's convert these moles to mass (mol . molar mass)
2.5 mol . 142.06 g/mol = 355.1 g
Excersise 7.
The reaction is:
Pb(SO₄)₂+ 4 LiNO₃ → Pb(NO₃)₄ + 2Li₂SO₄
As we assume that we have an adequate amount of lead (IV) sulfate, the limiting reactant is the lithium nitrate.
Let's convert the mass to moles (mass / molar mass)
250 g / 109.94 g/mol = 2.27 moles
Let's make a rule of three. Ratio is 2:4.
2 moles of lithium sulfate were produced by 4 moles of lithium nitrate
2.27 moles of Li₂SO₄ would have been produced by ( 2.27 .4) / 2 = 4.54 moles.
Let's convert these moles to mass (mol . molar mass)
4.54 mol . 68.94 g/mol = 313 g
Helium is the lightest noble gas and the second most abundant element (after hydrogen) in the universe. The mass of a helium−4 atom is 6.64648 × 10−24g, and each of its two electrons has a mass of 9.10939 × 10−28g. What fraction of this atom's mass is contributed by its nucleus?
The fraction of a helium-4 atom's mass contributed by its nucleus can be calculated using the relative masses of the nucleus and electrons.
When calculating the fraction of an atom's mass contributed by its nucleus, we consider the relative masses of the nucleus and the electrons. The mass of the nucleus is determined by subtracting the combined mass of the two electrons from the total mass of the helium-4 atom. So, the fraction of the atom's mass contributed by its nucleus is:
Nucleus fraction = (4 x mass of nucleon) / (4 x mass of nucleon + total mass of electrons)
Using the given values, the nucleus fraction of a helium-4 atom can be calculated.
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The fraction of the helium-4 atom's mass contributed by its nucleus is approximately 0.999927.
To find the fraction of the helium-4 atom's mass that is contributed by its nucleus, we need to subtract the mass of the electrons from the total mass of the atom and then divide by the total mass of the atom.
The mass of a helium-4 atom is given as [tex]\( m_{atom} = 6.64648 \times 10^{-24} \) g[/tex].
Each helium-4 atom has two electrons, and the mass of each electron is [tex]\( m_{electron} = 9.10939 \times 10^{-28} \) g[/tex].
First, we calculate the total mass of the two electrons:
[tex]\[ m_{electrons\_total} = 2 \times m_{electron} = 2 \times 9.10939 \times 10^{-28} \text{ g} \][/tex]
[tex]\[ m_{electrons\_total} = 18.21878 \times 10^{-28} \text{ g} \][/tex]
Next, we find the mass of the nucleus by subtracting the total mass of the electrons from the total mass of the atom:
[tex]\[ m_{nucleus} = m_{atom} - m_{electrons\_total} \][/tex]
[tex]\[ m_{nucleus} = 6.64648 \times 10^{-24} \text{ g} - 18.21878 \times 10^{-28} \text{ g} \][/tex]
[tex]\[ m_{nucleus} \approx 6.64648 \times 10^{-24} \text{ g} \][/tex]
(Note that the mass of the electrons is negligible compared to the mass of the nucleus, so the subtraction does not significantly change the value of [tex]\( m_{nucleus} \)[/tex].)
Now, we calculate the fraction of the atom's mass that is contributed by the nucleus:
[tex]\[ \text{Fraction} = \frac{m_{nucleus}}{m_{atom}} \][/tex]
[tex]\[ \text{Fraction} \approx \frac{6.64648 \times 10^{-24} \text{ g}}{6.64648 \times 10^{-24} \text{ g}} \][/tex]
[tex]\[ \text{Fraction} \approx 1 - \frac{18.21878 \times 10^{-28} \text{ g}}{6.64648 \times 10^{-24} \text{ g}} \][/tex]
[tex]\[ \text{Fraction} \approx 1 - 2.742 \times 10^{-4} \][/tex]
[tex]\[ \text{Fraction} \approx 0.999927 \][/tex]
Therefore, the fraction of the helium-4 atom's mass contributed by its nucleus is approximately 0.999927."
If your hot coffee sits on your desktop and loses 50 kJ of energy duringcooling, what is the quantitative change in enthalpy of the coffee?
Answer : The change in enthalpy of the coffee is negative.
Explanation :
Endothermic reaction : It is defined as the chemical reaction in which the energy is absorbed from the surrounding.
In the endothermic reaction, the energy of reactant are less than the energy of product.
Exothermic reaction : It is defined as the chemical reaction in which the energy is released into the surrounding.
In the exothermic reaction, the energy of reactant are more than the energy of product.
Enthalpy change : It is the difference between the energy of product and the reactant. It is represented as [tex]\Delta H[/tex].
When the system gains energy in the form of heat then the change in enthalpy is positive.When the system loses energy in the form of heat then the change in enthalpy is negative.As per question, if hot coffee sits on your desktop and loses 50 kJ of energy during cooling, the change in enthalpy of the coffee is negative.
Hence, change in enthalpy of the coffee is negative.
Combustion reactions are exothermic. The heat of reaction for the combustion of cyclopropane, C3H6, is 499.8 kcal/mol. What is the heat of combustion for cyclopropane in kcal/gram?
To find the heat of combustion for cyclopropane in kcal/gram, divide the heat of reaction (499.8 kcal/mol) by the molar mass of cyclopropane (42.08 g/mol).
Explanation:The heat of combustion for cyclopropane in kcal/gram can be calculated using its molar mass and the given heat of reaction. The molar mass of cyclopropane, C3H6, is 42.08 g/mol. With a heat of reaction of 499.8 kcal/mol, we can calculate the heat of combustion per gram by dividing the heat of reaction by the molar mass:
Heat of combustion (kcal/g) = Heat of reaction (kcal/mol) / Molar mass (g/mol)
Thus,
Heat of combustion (kcal/g) = 499.8 kcal/mol / 42.08 g/mol
Once you perform the division, you'll have the heat of combustion for cyclopropane in kcal/gram.
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A 31.4−g sample of ethylene glycol, a car radiator coolant, loses 607 J of heat. What was the initial temperature of the ethylene glycol if the final temperature is 32.5°C? (c of ethylene glycol = 2.42 J/g·K
The initial temperature of the ethylene glycol is equal to 40.5°C.
What is the specific heat capacity?The specific heat capacity is defined as the amount of heat required to raise the temperature of one unit of material by one degree Celsius. The specific heat capacity of the material depends upon the nature of the material.
The mathematical expression is used to calculate the specific heat is equal to:
[tex]Q = mC \triangle T[/tex]
Given, the mass of the sample of ethylene glycol, m = 31.4 g
The final temperature of the sample, T₂ = 32.5°C = 305.5 K
The specific heat capacity of ethylene glycol, C = 2.42 J/g·K
The heat lost from the sample, Q = - 607 J
The initial temperature of the sample:
- 607 = 31.4 × 2.42 × (305.5 - T₁)
305.5 - T₁ = - 7.988
T₁ = 313.49 K
T₁ = 40.5°C
Therefore, the initial temperature of the ethylene glycol is 40.5°C.
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The initial temperature of ethylene glycol can be found by rearranging the equation q = mcΔT and dividing the heat lost by the product of the mass and specific heat capacity, considering the known final temperature and that the ethylene glycol is cooling down.
Explanation:To calculate the initial temperature of ethylene glycol when it loses heat, we can use the equation that relates heat loss to temperature change, q = mcΔT, where q is the heat lost, m is the mass, c is the specific heat capacity of the substance, and ΔT is the change in temperature. Given that ethylene glycol loses 607 J of heat (q), has a mass of 31.4g (m), and a specific heat capacity of 2.42 J/g·°C (c), and the final temperature is 32.5°C, we can rearrange the equation to solve for the initial temperature, T_initial.
The heat lost is negative because the ethylene glycol is cooling down, so we have: -607 J = 31.4g × 2.42 J/g·K × (32.5°C - T_initial). Solving for T_initial we find that the initial temperature of the ethylene glycol is higher than the final temperature of 32.5°C by an amount resultant from dividing the heat lost by the product of the mass and the specific heat capacity.
Which of the following precautions is important when using a Bunsen burner or Meker burner?a. Set up your work space so that wires and cables cannot accidentally make contact with the flame or hot glassware and meltb. Set up your work space with the burner in a secure location away from the edge of the benchc. Set up the work space so that flammable materials are away from the burnerd. Never leave an open flame unattendede. Remember that any glassware heated by the burner will look the same when hot as cold, and it will take a while to coolf. Always tie back hair
Answer:
Never leave an open flame unattended
Explanation: if an open flame is left unattended it can cause a fire outbreak so we have to watch it at all times to prevent the fire outbreak
What is the molality of a solution made up of 43.6 mol of CACI₂ dissolved in 13.5 kg of water? Please Show work
Answer:
The answer to your question is m = 3.2
Explanation:
Molality is defined as the number of moles of a solute dissolved in a mass of solvent (kg).
Data
moles of solute = 43.6
mass of solvent = 13.5 kg
Formula
Molality = [tex]\frac{number of moles}{Kg of solvent}[/tex]
Substitution
Molality = [tex]\frac{43.6}{13.5}[/tex]
Simplification and result
Molality = 3.2
What type of chemical bond joins a functional group to the carbon skeleton of a large molecule?
Answer:
Covalent bond
Explanation:
Functional groups can be defined as a group of atoms or ions responsible for the properties particular to a certain group of organic compounds. What we are saying in essence is that it is the functional groups that decides the behavior of the organic compound in question.
Covalent linkages are the mechanism through which these functional groups are linked to the carbon skeleton of the compound to which they belong. Covalent bonding is a type of chemical bonding which in there is sharing of electrons between atoms
Covalent bond
Aliphatic hydrocarbons are divided into three main groups according to the types of bonds they contain: alkanes, alkenes, and alkynes. Alkanes have only single bonds, alkenes contain a carbon-carbon double bond, and alkynes contain a carbon-carbon triple bond.A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. Carbon skeletons are the backbones of organic molecules. They are composed of carbon-carbon atoms that form chains to make an organic compound.Learn more:
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In every chemical reaction, ____.
a) moles and liters are conserved
b) moles and molecules are conserved
c) mass and atoms are conserved
d) mass and molecules are conserved
Answer:
c) mass and atoms are conserved
Explanation:
Law of conservation of mass -
In a chemical reaction ,
The mass and atoms of the chemical reaction are conserved ,
According to the Antoine Lavoisier ,
During a chemical reaction ,
Atoms and mass can neither be formed nor be deleted , there is only transfer of atoms and mass .
Hence , from the given question ,
The correct option is c.
In every chemical reaction, mass and atoms are conserved.
Explanation:The correct answer is c) mass and atoms are conserved in every chemical reaction.
According to the Law of Conservation of Mass, the total mass of the reactants must be equal to the total mass of the products in a chemical reaction.
Additionally, the Law of Conservation of Atoms states that the number of atoms of each element must be equal on both sides of the chemical equation.
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Solid NH4HS is introduced into an evacuated flask at 24 ∘C. The following reaction takes place: NH4HS(s)⇌NH3(g)+H2S(g) At equilibrium the total pressure (for NH3 and H2S taken together) is 0.614 atm.
Answer:
0.09425
Explanation:
The reactant is in solid phase and therefore has zero partial pressure.
The products have the same mole ratio (1:1) and will have the same partial pressure = 1/2 × 0.614 atm = 0.307 atm
Kp = (NH3)(H2S) = 0.09425
The equilibrium constant expression for the given reaction is K = [NH3][H2S]. Since NH4HS is a solid, it is not included in the equilibrium constant expression. If the concentration of H2S triples, the concentration of NH3 should decrease by a factor of 3 to maintain equilibrium.
Explanation:The given reaction involving NH4HS(s)⇌NH3(g)+H2S(g) is an equilibrium reaction. At equilibrium, the total pressure of NH3 and H2S combined is 0.614 atm. In this equilibrium expression, NH4HS(s) does not appear since it is a solid. Therefore, the equilibrium constant, K, is given by the expression K = [NH3][H2S]. Since the concentrations of the products are inversely proportional, if the H2S concentration triples, the NH3 concentration must decrease by a factor of 3 to keep the system at equilibrium so that the product of the concentrations equals K.