Question 1

Which of the following information items would be most useful in verifying the law of definite proportions?

Accepted Answer

The law of definite proportions states that a chemical compound always contains its component elements in fixed ratio by mass and does not depend on its source and method of preparation. Therefore, analyzing samples of a pure compound collected from various locations and finding that they have the same elemental composition by mass would directly verify this law.

Question 2

According to the law of definite proportions, if a sample of a compound contains 24.00 grams of carbon and 4.00 grams of hydrogen, then another sample of the same compound which contains 48.0 grams of carbon must contain ________.

Accepted Answer

The law of definite proportions states that a chemical compound always contains its component elements in fixed ratio by mass and does not depend on its source and method of preparation. Therefore, if the first sample has 24.00 grams of carbon and 4.00 grams of hydrogen, doubling the amount of carbon to 48.0 grams would also double the amount of hydrogen to 8.00 grams to maintain the fixed ratio of elements in the compound.

Question 3

What is the formula weight of Ba(C₂H₃O₂)₂ in grams per mole?

Accepted Answer

B

Question 4

Which of the following compounds has the largest formula mass?

Accepted Answer

D (Carbon tetrachloride, CCl4) has the largest formula mass because it contains one carbon atom and four chlorine atoms, which collectively have a higher mass than the elements in the other options.

Question 5

The formula mass of (NH₄)₃PO₄, is ________.

Accepted Answer

The formula given is for NH4PO4. To find the formula mass, add the atomic masses of all atoms: N (14.01 amu) + 4H (4 * 1.01 amu) + P (30.97 amu) + 4O (4 * 16.00 amu) = 14.01 + 4.04 + 30.97 + 64.00 = 149.02 amu. The correct answer is closest to 149.12 amu.

Question 6

Glucose is the type of sugar the human body metabolizes to produce energy. Calculate the formula mass of glucose, C₆H₁₂O₆.

Accepted Answer

The formula for glucose is C6H12O6. Calculating the formula mass: Carbon (C) has an atomic mass of about 12.01 amu, Hydrogen (H) about 1.01 amu, and Oxygen (O) about 16.00 amu. Thus, the formula mass of glucose is (6*12.01) + (12*1.01) + (6*16.00) = 72.06 + 12.12 + 96.00 = 180.18 amu.

Question 7

What is the molar mass of crotonaldehyde (C₄H₆O)?

Accepted Answer

The answer of What is the molar mass of crotonaldehyde...

Question 8

The mass percentage of Cl in the compound KClO₃ is ________.

Accepted Answer

The answer of The mass percentage of Cl in the...

Question 9

In which of the following compounds is the mass percentage of calcium the greatest?

Accepted Answer

The answer of In which of the following compounds is...

Question 10

In which of the following samples will the mass percentage H be the greatest?

Accepted Answer

The mass percentage of an element in a compound is independent of the amount of the compound. It is determined by the compound's formula, not by how much of it you have. Therefore, all samples of C12H16 have the same mass percentage of hydrogen.

Question 11

A 2.00 g sample of cholesterol contains 1.68 g C, 0.24 g H, and 0.080 g O. What is the percent composition of oxygen in cholesterol?

Accepted Answer

The percent composition of an element in a compound is calculated by dividing the mass of the element in the compound by the total mass of the compound and then multiplying by 100. For oxygen in cholesterol, this is (0.080 g / 2.00 g) * 100 = 4.0%.

Question 12

Calculate the percentage composition of oxygen in Ca(C₂H₃O₂)₂.

Accepted Answer

The answer of Calculate the percentage composition of oxygen in...

Question 13

The mass percent of chlorine in Mg(ClO₃)₂ is ________.

Accepted Answer

To find the mass percent of chlorine in Mg(ClO_4)_2, first calculate the molar mass of the compound. The molar mass of magnesium (Mg) is approximately 24.31 g/mol, chlorine (Cl) is about 35.45 g/mol, and oxygen (O) is 16.00 g/mol. The formula Mg(ClO_4)_2 includes one magnesium atom, two chlorine atoms, and eight oxygen atoms. The molar mass of Mg(ClO_4)_2 = 24.31 (Mg) + 2(35.45) (Cl) + 8(16.00) (O) = 24.31 + 70.9 + 128 = 223.21 g/mol.The mass of chlorine in one mole of Mg(ClO_4)_2 = 2(35.45) = 70.9 g.The mass percent of chlorine = (mass of Cl / molar mass of Mg(ClO_4)_2) * 100 = (70.9 / 223.21) * 100 ≈ 31.8%.However, given the options provided and acknowledging a potential calculation or typographical error in the question or answer choices, the closest correct option based on the calculation method is not directly listed. The calculation provided should yield a result around 31.8%, but since this option is not available and assuming a mistake in my calculation or interpretation, the correct methodology involves calculating the mass of chlorine relative to the total mass and then multiplying by 100 to get the percentage. Without the exact numbers aligning to the provided choices, the instructional intent is to demonstrate how to approach the calculation.

Question 14

What is the mass percent of carbon in dimethyl sulfoxide, C₂H₆SO?

Accepted Answer

The molecular formula for dimethyl sulfoxide is $C_2H_6SO$. To find the mass percent of carbon, first calculate the molar mass of the compound: $2 \times 12.01$ (carbon) + $6 \times 1.008$ (hydrogen) + $32.07$ (sulfur) + $16.00$ (oxygen) = $78.13 \, \text{g/mol}$. The mass of carbon in the compound is $2 \times 12.01 = 24.02 \, \text{g}$. The mass percent of carbon is $\frac{24.02}{78.13} \times 100\% = 30.7\%$.

Question 15

Calculate the percentage composition of oxygen in K₂CO₃.

Accepted Answer

The molar mass of K2CO3 is 138.205 g/mol. The molar mass of oxygen in K2CO3 is 48.00 g/mol (3 x 16.00 g/mol). The percentage composition of oxygen is (48.00/138.205) x 100% = 34.73%.

Question 16

Nicotine (C₁₀H₁₄N₂) is a byproduct of the tobacco industry and is used as an agricultural insecticide. Calculate the percent composition of each element in nicotine.

Accepted Answer

The molecular formula of nicotine is C10H14N2. To calculate the percent composition, first calculate the molar mass: C (12.01 g/mol) * 10 = 120.1 g/mol, H (1.008 g/mol) * 14 = 14.112 g/mol, N (14.01 g/mol) * 2 = 28.02 g/mol. Total molar mass = 162.232 g/mol. Percent composition: C = (120.1/162.232)*100 = 74.0%, H = (14.112/162.232)*100 = 8.70%, N = (28.02/162.232)*100 = 17.3%.

Question 17

Which of the following statements concerning the numerical value 6.02 x 10²³ is incorrect?

Accepted Answer

C) is incorrect because 6.02 x 10^23 (Avogadro's number) represents the number of particles (atoms, molecules, ions, etc.) in one mole of a substance, not the mass. The mass of one mole of any substance, in grams, is equal to its molecular or atomic mass, not a fixed numerical value like Avogadro's number.

Question 18

Which of the following quantities does not contain the same number of atoms as there are in 80.2 grams of Ca?

Accepted Answer

The answer of Which of the following quantities does not...

Question 19

How many Cl atoms are present in 2.16 moles of NCl₃?

Accepted Answer

The number of Cl atoms in 2.16 moles of NCl3 can be calculated using the following steps:1. Convert moles of NCl3 to moles of Cl atoms:2.16 moles NCl3 x (3 moles Cl atoms / 1 mole NCl3) = 6.48 moles Cl atoms2. Convert moles of Cl atoms to number of Cl atoms:6.48 moles Cl atoms x (6.022 x 10^23 atoms / 1 mole) = 3.90 x 10^24 Cl atomsTherefore, the correct answer is C) 3.90 x 10^24 Cl atoms.

Question 20

Calculate the mass (grams) of 0.750 moles of Al₂(Cr₂O₇)₃.

Accepted Answer

The molecular formula for Al2(Cr2O7)3 involves calculating the molar mass by adding the atomic masses of all atoms: 2 Al (26.98 g/mol each), 6 Cr (51.9961 g/mol each), and 21 O (15.999 g/mol each). The total molar mass is approximately 701.68 g/mol. For 0.750 moles, the mass is 0.750 moles * 701.68 g/mol ≈ 526.26 g, which rounds to 526 g.

Quiz 9: Chemical Calculations: the Mole Concept and Chemical Formulas

Which of the following information items would be most useful in verifying the law of definite proportions?

According to the law of definite proportions, if a sample of a compound contains 24.00 grams of carbon and 4.00 grams of hydrogen, then another sample of the same compound which contains 48.0 grams of carbon must contain ________.

What is the formula weight of Ba(C₂H₃O₂) ₂ in grams per mole?

Which of the following compounds has the largest formula mass?

The formula mass of (NH₄) ₃PO₄, is ________.

Glucose is the type of sugar the human body metabolizes to produce energy. Calculate the formula mass of glucose, C₆H₁₂O₆.

What is the molar mass of crotonaldehyde (C₄H₆O) ?

The mass percentage of Cl in the compound KClO₃ is ________.

In which of the following compounds is the mass percentage of calcium the greatest?

In which of the following samples will the mass percentage H be the greatest?

A 2.00 g sample of cholesterol contains 1.68 g C, 0.24 g H, and 0.080 g O. What is the percent composition of oxygen in cholesterol?

Calculate the percentage composition of oxygen in Ca(C₂H₃O₂) ₂.

The mass percent of chlorine in Mg(ClO₃) ₂ is ________.

What is the mass percent of carbon in dimethyl sulfoxide, C₂H₆SO?

Calculate the percentage composition of oxygen in K₂CO₃.

Nicotine (C₁₀H₁₄N₂) is a byproduct of the tobacco industry and is used as an agricultural insecticide. Calculate the percent composition of each element in nicotine.

Which of the following statements concerning the numerical value 6.02 x 10²³ is incorrect?

Which of the following quantities does not contain the same number of atoms as there are in 80.2 grams of Ca?

How many Cl atoms are present in 2.16 moles of NCl₃?

Calculate the mass (grams) of 0.750 moles of Al₂(Cr₂O₇) ₃.

Quiz 9: Chemical Calculations: the Mole Concept and Chemical Formulas

Which of the following information items would be most useful in verifying the law of definite proportions?

According to the law of definite proportions, if a sample of a compound contains 24.00 grams of carbon and 4.00 grams of hydrogen, then another sample of the same compound which contains 48.0 grams of carbon must contain ________.

What is the formula weight of Ba(C2H3O2) 2 in grams per mole?

Which of the following compounds has the largest formula mass?

The formula mass of (NH4) 3PO4, is ________.

Glucose is the type of sugar the human body metabolizes to produce energy. Calculate the formula mass of glucose, C6H12O6.

What is the molar mass of crotonaldehyde (C4H6O) ?

The mass percentage of Cl in the compound KClO3 is ________.

In which of the following compounds is the mass percentage of calcium the greatest?

In which of the following samples will the mass percentage H be the greatest?

A 2.00 g sample of cholesterol contains 1.68 g C, 0.24 g H, and 0.080 g O. What is the percent composition of oxygen in cholesterol?

Calculate the percentage composition of oxygen in Ca(C2H3O2) 2.

The mass percent of chlorine in Mg(ClO3) 2 is ________.

What is the mass percent of carbon in dimethyl sulfoxide, C2H6SO?

Calculate the percentage composition of oxygen in K2CO3.

Nicotine (C10H14N2) is a byproduct of the tobacco industry and is used as an agricultural insecticide. Calculate the percent composition of each element in nicotine.

Which of the following statements concerning the numerical value 6.02 x 1023 is incorrect?

Which of the following quantities does not contain the same number of atoms as there are in 80.2 grams of Ca?

How many Cl atoms are present in 2.16 moles of NCl3?

Calculate the mass (grams) of 0.750 moles of Al2(Cr2O7) 3.

What is the formula weight of Ba(C₂H₃O₂) ₂ in grams per mole?

The formula mass of (NH₄) ₃PO₄, is ________.

Glucose is the type of sugar the human body metabolizes to produce energy. Calculate the formula mass of glucose, C₆H₁₂O₆.

What is the molar mass of crotonaldehyde (C₄H₆O) ?

The mass percentage of Cl in the compound KClO₃ is ________.

Calculate the percentage composition of oxygen in Ca(C₂H₃O₂) ₂.

The mass percent of chlorine in Mg(ClO₃) ₂ is ________.

What is the mass percent of carbon in dimethyl sulfoxide, C₂H₆SO?

Calculate the percentage composition of oxygen in K₂CO₃.

Nicotine (C₁₀H₁₄N₂) is a byproduct of the tobacco industry and is used as an agricultural insecticide. Calculate the percent composition of each element in nicotine.

Which of the following statements concerning the numerical value 6.02 x 10²³ is incorrect?

How many Cl atoms are present in 2.16 moles of NCl₃?

Calculate the mass (grams) of 0.750 moles of Al₂(Cr₂O₇) ₃.