# chemistry lab

Topics: Molar mass, Water, Ideal gas law Pages: 25 (3757 words) Published: September 21, 2014
Regents Chemistry

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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