chemistry lab

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