Question

name___ period_ date___chapter 7 review worksheetcalculate the molar mass for the following-1) $ce{h2so4}$2) $ce{nh4br}$3) $ce{cacl2}$4) $ce{caco3}$5) $ce{fe2o3}$calculate the moles for the following-6) 234g $ce{h2so4}$7) 47.4g $ce{nh4br}$8) 127g $ce{cacl2}$9) 78g $ce{caco3}$10) 15.1g $ce{fe2o3}$calculate the mass for the following-11) 2.25 moles $ce{h2so4}$12) 1.75 moles $ce{nh4br}$13) 3.0 moles $ce{cacl2}$14) 4.3 moles $ce{caco3}$15) .75 moles $ce{fe2o3}$

Explanation:

Molar Mass Calculations (1-5)

Step1: Use atomic masses (H=1, S=32, O=16, N=14, Br=80, Ca=40, Cl=35.5, Fe=56)

Step2: Sum atomic masses for each compound

1. $\text{H}_2\text{SO}_4$: $2(1) + 32 + 4(16) = 2 + 32 + 64 = 98\ \text{g/mol}$
2. $\text{NH}_4\text{Br}$: $14 + 4(1) + 80 = 14 + 4 + 80 = 98\ \text{g/mol}$
3. $\text{CaCl}_2$: $40 + 2(35.5) = 40 + 71 = 111\ \text{g/mol}$
4. $\text{CaCO}_3$: $40 + 12 + 3(16) = 40 + 12 + 48 = 100\ \text{g/mol}$
5. $\text{Fe}_2\text{O}_3$: $2(56) + 3(16) = 112 + 48 = 160\ \text{g/mol}$

Mole Calculations (6-10)

Step1: Use formula $n = \frac{m}{M}$ (n=moles, m=mass, M=molar mass)

Step2: Substitute values for each substance

1. $\text{H}_2\text{SO}_4$: $n = \frac{234}{98} \approx 2.39\ \text{mol}$
2. $\text{NH}_4\text{Br}$: $n = \frac{47.4}{98} \approx 0.48\ \text{mol}$
3. $\text{CaCl}_2$: $n = \frac{127}{111} \approx 1.14\ \text{mol}$
4. $\text{CaCO}_3$: $n = \frac{78}{100} = 0.78\ \text{mol}$
5. $\text{Fe}_2\text{O}_3$: $n = \frac{15.1}{160} \approx 0.094\ \text{mol}$

Mass Calculations (11-15)

Step1: Use formula $m = n \times M$ (m=mass, n=moles, M=molar mass)

Step2: Substitute values for each substance

1. $\text{H}_2\text{SO}_4$: $m = 2.25 \times 98 = 220.5\ \text{g}$
2. $\text{NH}_4\text{Br}$: $m = 1.75 \times 98 = 171.5\ \text{g}$
3. $\text{CaCl}_2$: $m = 3.0 \times 111 = 333\ \text{g}$
4. $\text{CaCO}_3$: $m = 4.3 \times 100 = 430\ \text{g}$
5. $\text{Fe}_2\text{O}_3$: $m = 0.75 \times 160 = 120\ \text{g}$

Answer:

1. $98\ \text{g/mol}$
2. $98\ \text{g/mol}$
3. $111\ \text{g/mol}$
4. $100\ \text{g/mol}$
5. $160\ \text{g/mol}$
6. $\approx 2.39\ \text{mol}$
7. $\approx 0.48\ \text{mol}$
8. $\approx 1.14\ \text{mol}$
9. $0.78\ \text{mol}$
10. $\approx 0.094\ \text{mol}$
11. $220.5\ \text{g}$
12. $171.5\ \text{g}$
13. $333\ \text{g}$
14. $430\ \text{g}$
15. $120\ \text{g}$