Q: What is the mass percent of fluorine in $$C_2HBrClF_3$$? (Molar mass = 197.38 g/mol, atomic mass of F = 18.998 g/mol)

$$\frac{3 \times 18.998}{197.38} \times 100\% = 28.9\%$$

Q: A 55.0 mph car is traveling at what speed in meters per minute? (1 mile = 1609 m, 1 hour = 60 min)

$$55.0 \times \frac{1609}{1} \times \frac{1}{60} = 1475 m/$$min

Question 1

Which of the following is the correct empirical formula for a compound with a molecular formula of $$C_5H_{12}$$?

Accepted Answer

$$C_5H_{12}$$ \div 1 = C_5H_{12}$$, so the empirical formula is C_5H$$_{12}$

Question 2

A sample of vitamin C weighing 0.2000 g produces 0.2998 g $$CO_2$$ and 0.0819 g $$H_2O$$ upon combustion. What is the first step in determining the empirical formula of vitamin C?

Accepted Answer

Convert the mass of $$CO_2$$ and $$H_2O to $$moles of C and H, respectively.

Question 3

Which of the following statements about significant figures is correct?

Accepted Answer

Leading zeros are not significant.

Question 4

What is the mass percent of fluorine in $$C_2HBrClF_3$$? (Molar mass = 197.38 g/mol, atomic mass of F = 18.998 g/mol)

Accepted Answer

$$\frac{3 	imes 18.998}{197.38} 	imes 100\% = 28.9\%$$

Question 5

Which of the following is a molecular element?

Accepted Answer

Oxygen ($$O_2)$$

Question 6

A 55.0 mph car is traveling at what speed in meters per minute? (1 mile = 1609 m, 1 hour = 60 min)

Accepted Answer

$$55.0 	imes \frac{1609}{1} 	imes \frac{1}{60} = 1475 m/$$min

Question 7

Which of the following best describes the structure of sodium chloride ($$NaCl) in $$the solid state?

Accepted Answer

A three-dimensional lattice of alternating $$Na^+$$ and $$Cl^-$$ ions

Question 8

Which of the following is an example of an allotrope?

Accepted Answer

Diamond and graphite (both forms of carbon)

Question 9

How many significant figures should the answer have for the calculation $$(3.23 	imes 0.02704) / (250. 	imes 15)$$?

Accepted Answer

2

Question 10

Which of the following is the correct balanced equation for the combustion of ethane ($$C_2H_6) in $$oxygen?

Accepted Answer

$$2C_2H_6 + 7O_2 \rightarrow 4CO_2 + 6H_2O$$

Question 11

A chemist finds a compound is 57.14% C, 6.16% H, 9.52% N, and the rest O. What is the first step to determine its empirical formula?

Accepted Answer

Convert the percentages to grams (assuming 100 g sample)

Question 12

Which of the following is a correct statement about the use of molar mass as a conversion factor?

Accepted Answer

Molar mass allows conversion between grams and moles of a substance.

Question 13

Which of the following is a polyatomic element?

Accepted Answer

Sulfur ($$S_8)$$

Question 14

Which of the following is the correct process for determining the empirical formula from percent composition?

Accepted Answer

Convert percent to grams, grams to moles, divide by smallest number of moles, write formula

Question 15

Which of the following is an example of a molecular compound?

Accepted Answer

Water ($$H_2O)$$

Question 16

A 1.0 $$\muL $$sample of ethyl mercaptan ($$C_2H_6S) $$has a density of 0.84 g/mL. How many molecules are in the sample? (Molar mass = 62.14 g/mol, $$1 mL$$ = $$10^3$$ $$\muL$$, $$N_A = 6.022 	imes 10$$^{23}$$)

Accepted Answer

$$1.36 	imes 10$$^{19}$$ molecules

Question 17

Which of the following is true about the metallic character trend in the periodic table?

Accepted Answer

Metallic character increases down a group and decreases across a period.

Question 18

Which of the following is an example of a homogeneous mixture?

Accepted Answer

Sweetened tea

Question 19

Which of the following is the correct definition of an ionic bond?

Accepted Answer

A bond formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions.

General Chemistry Study Guide: Matter, Measurement, Atoms, Compounds, and Chemical Quantities

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