# chemistry lab

Quarter 1 Midterm Review

1. The percent by mass of oxygen in Na2SO4

(formula mass = 142) is closest to

1) 11%

3) 45%

2) 22%

4) 64%

2. Given the unbalanced equation:

__Al(s) + __O2(g) → __Al2O3(s)

3.

4.

5.

6.

7.

balance the equation using smallest whole

number coefficients.

The percent by mass of aluminum in Al2O3 is

approximately

1) 18.9

3) 47.1

2) 35.4

4) 52.9

What is the approximate percent composition by

mass of CaBr2 (formula mass = 200)?

1) 20% calcium and 80% bromine

2) 25% calcium and 75% bromine

3) 30% calcium and 70% bromine

4) 35% calcium and 65% bromine

What is the empirical formula for C3H6?

1) CH

2) CH2

3) CH3

4) CH6

Which represents both an empirical and a

molecular formula?

1) P2O5

2) N2O4

3) C3H6

4) C6H12O6

The number of atoms in 2 grams of calcium is

equal to

1) 2 × 6.02 × 1023

40

2) 40 × 6.02 × 1023

2

3) 6.02 × 1023

2 × 40

4) 2 × 40 × 6.02 × 1023

8. At STP, 32 grams of O2 would occupy the same

volume as

1) 64 g of H2

2) 32 g of SO2

3) 8.0 g of CH4

4) 4.0 g of He

9. Which compound has the empirical formula CH2

O?

1) CH3OH

2) CH3CH2OH

3) HCOOH

4) CH3COOH

10. Which list consists of types of chemical

formulas?

1) atoms, ions, molecules

2) metals, nonmetals, metalloids

3) empirical, molecular, structural

4) synthesis, decomposition, neutralization

11. What is the total number of neon atoms

contained in 20.2 grams of neon gas?

3) 3.01 × 1023

1) 1.01 × 1024

2) 2.02 × 1024

4) 6.02 × 1023

12. Given the balanced equation:

X + Cl2 - C2H5Cl + HCl

Which molecule is represented by X?

1) C2H4

2) C2H6

3) C3H6

4) C3H8

13. Which equation is correctly balanced?

3) 2 H2 + O2 → 2 H2O

1) H2 + O2 → H2O

2) Ca + Cl2 → CaCl

4) Ca + C12 → Ca2Cl

14. Given the unbalanced equation:

__Al2(SO4)3 + __Ca(OH)2 → __Al(OH)3 +

__CaSO4

Balance the equation using smallest whole

number coefficients.

Quarter 1 Midterm Review

15. At STP, 25.0 liters of a gas has a mass of 50.0

grams. What is the gram molecular mass of the

gas?

1) 75.0 g

3) 25.0 g

2) 44.8 g

4) 11.2 g

16. In which compound is the percent by mass of

oxygen greatest?

1) BeO

3) CaO

2) MgO

4) SrO

17. What is the total mass of oxygen in 1.00 mole of

Al2(CrO4)3?

1) 192 g

3) 64.0 g

2) 112 g

4) 48.0 g

18. The percentage by mass of Br in the compound

AlBr3 is closest to

1) 10.%

3) 75%

2) 25%

4) 90.%

19. Given the unbalanced equation:

_C3H8(g) + _O2(g) → _H2O(g) + _CO2

(g)

Balance the equation using smallest whole

number coefficients.

20. In a laboratory experiment, a student determined the mass of the product, NaNO3(s), to be 0.105 grams. a. Calculate the gram formula mass of NaNO3(s). Round atomic masses from the Periodic Table to the nearest tenth. [ Show all work. Indicate the correct answer in proper significant figures and include an appropriate unit.] b. Calculate the number of moles of NaNO3(s) produced. [Show all work. Indicate the correct answer in proper significant figures.]

21. Which sample contains the same number of

atoms as 24 grams of carbon?

1) 80. g Ar

3) 10. g Ne

2) 24 g Mg

4) 4.0 g He

22. Given the reaction:

2 NaOH + H2SO4 → Na2SO4 + 2 H2O

What is the total number of moles of NaOH

needed to react completely with 2 moles of H2

SO4?

1) 1

3) 0.5

2) 2

4) 4

23. What is the total number of atoms represented in

the formula CuSO4 • 5H2O?

1) 8

3) 21

2) 13

4) 27

24. How many molecules are in 0.25 mole of O2?

3) 3.0 × 1023

1) 12 × 1023

2) 6.0 × 1023

4) 1.5 × 1023

25. Which substance can be decomposed by a

chemical change?

1) Co

3) Cr

2) CO

4) Cu

26. What is the total number of molecules of

hydrogen in 0.25 mole of hydrogen?

3) 3.0 × 1023

1) 6.0 × 1023

2) 4.5 × 1023

4) 1.5 × 1023

Quarter 1 Midterm

Review

27. What is the total number of moles of oxygen

30. Which particle diagram represents a mixture of

atoms in 1 mole of ozone? (Molecular mass =

48)

1) 1

3) 3

2) 2

4) 4...

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