Q: If 84.2 g of pitchblende contains 71.4 g of uranium, how many grams of uranium can be obtained from 102 kg of pitchblende?

$$102 \times \frac{71.4}{84.2} \times 1000 = 8.65 \times 10^4$ g$

Q: Calculate the atomic mass of silver given the following data: $$^{107}Ag ($$mass $$= 106.90509$$ amu, abundance $$= 51.84\%$$), $$^{109}Ag ($$mass $$= 108.90476$$ amu, abundance $$= 48.16\%).$$

$$106.90509 \times 0.5184 + 108.90476 \times 0.4816 = 107.87$$ amu

Q: Calculate the molecular mass of $$NH_4NO_3$$ using the following atomic masses: N = 14.01 amu, H = 1.008 amu, O = 16.00 amu.

$$(2 \times 14.01) + (4 \times 1.008) + (3 \times 16.00) = 80.05$$ amu

Question 1

Which of the following best describes the difference between an element and a compound?

Accepted Answer

An element cannot be broken down into simpler substances by chemical means, while a compound can.

Question 2

According to Dalton’s Atomic Theory, which statement is correct regarding atoms during a chemical reaction?

Accepted Answer

Atoms are rearranged, but not created or destroyed.

Question 3

A sample of calcium carbonate contains 8.0 g calcium, 2.4 g carbon, and 9.6 g oxygen. What is the mass fraction of oxygen in this sample?

Accepted Answer

$$\frac{9.6}{20.0} = 0.48$$

Question 4

Which law is illustrated by the fact that the total mass of reactants equals the total mass of products in a chemical reaction?

Accepted Answer

Law of Mass Conservation

Question 5

If 84.2 g of pitchblende contains 71.4 g of uranium, how many grams of uranium can be obtained from 102 kg of pitchblende?

Accepted Answer

$$102 	imes \frac{71.4}{84.2} 	imes 1000 = 8.65 	imes 10^4$ g$

Question 6

Which statement best explains the Law of Definite Composition?

Accepted Answer

A compound is always composed of the same elements in the same parts by mass.

Question 7

Given two compounds formed from elements A and B, the masses of B that combine with a fixed mass of A are in a ratio of small whole numbers. Which law does this illustrate?

Accepted Answer

Law of Multiple Proportions

Question 8

Which experiment led to the discovery of the atomic nucleus?

Accepted Answer

Rutherford’s alpha-scattering experiment

Question 9

Which subatomic particle has a relative mass of approximately $$0.00054858$$ amu and a charge of $$-1.60218 	imes 10$$^{-19}$$ C?

Accepted Answer

Electron

Question 10

How many protons, neutrons, and electrons are present in the isotope $$^{29}_{14}Si$$?

Accepted Answer

14 protons, 15 neutrons, 14 electrons

Question 11

Calculate the atomic mass of silver given the following data: $$^{107}Ag ($$mass $$= 106.90509$$ amu, abundance $$= 51.84\%$$), $$^{109}Ag ($$mass $$= 108.90476$$ amu, abundance $$= 48.16\%).$$

Accepted Answer

$$106.90509 	imes 0.5184 + 108.90476 	imes 0.4816 = 107.87$$ amu

Question 12

Which group in the periodic table contains elements that are so stable they hardly ever react to form compounds?

Accepted Answer

Noble gases

Question 13

Which property distinguishes metals from nonmetals in the periodic table?

Accepted Answer

Metals are malleable and good conductors of electricity.

Question 14

What is the empirical formula for a compound formed from $$Mg^{2+}$$ and $$N^{3-}$$ ions?

Accepted Answer

$$Mg_3N_2$$

Question 15

Which of the following is the correct name for the compound $$Fe_2O_3$$?

Accepted Answer

Iron(III) oxide

Question 16

What is the formula for sodium sulfite?

Accepted Answer

$$Na_2SO_3$$

Question 17

Which separation technique is best for separating a solid precipitate from a liquid solution?

Accepted Answer

Filtration

Question 18

What is the correct name for $$HNO_2$$?

Accepted Answer

Nitrous acid

Question 19

Calculate the molecular mass of $$NH_4NO_3$$ using the following atomic masses: N = 14.01 amu, H = 1.008 amu, O = 16.00 amu.

Accepted Answer

$$(2 	imes 14.01) + (4 	imes 1.008) + (3 	imes 16.00) = 80.05$$ amu

Components of Matter and Atomic Theory: Study Notes for General Chemistry

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