Question

molar masses of compounds
use the formula and your periodic table to calculate the molar mass of each compound. you may round to a whole number.

1. $\text{na}_2\text{so}_4$
2. $\text{h}_2\text{o}$
3. $\text{co}_2$
4. $\text{ca(oh)}_2$
5. $\text{al}_2(\text{so}_4)_3$
6. $\text{mg}_3\text{n}_2$
7. $\text{sr(no}_3\text{)}_2$
8. $\text{(nh}_4\text{)}_2\text{co}_3$

Explanation:

Step1: Get atomic masses (rounded)

From periodic table:
Na=23, S=32, O=16, H=1, C=12, Ca=40, Al=27, Mg=24, N=14, Sr=88

Step2: Calculate $\text{Na}_2\text{SO}_4$

$2(23) + 32 + 4(16) = 46 + 32 + 64$

Step3: Calculate $\text{H}_2\text{O}$

$2(1) + 16 = 2 + 16$

Step4: Calculate $\text{CO}_2$

$12 + 2(16) = 12 + 32$

Step5: Calculate $\text{Ca(OH)}_2$

$40 + 2(16+1) = 40 + 2(17)$

Step6: Calculate $\text{Al}_2(\text{SO}_4)_3$

$2(27) + 3[32 + 4(16)] = 54 + 3(32+64)$

Step7: Calculate $\text{Mg}_3\text{N}_2$

$3(24) + 2(14) = 72 + 28$

Step8: Calculate $\text{Sr(NO}_3\text{)}_2$

$88 + 2[14 + 3(16)] = 88 + 2(14+48)$

Step9: Calculate $(\text{NH}_4)_2\text{CO}_3$

$2(14+4(1)) + 12 + 3(16) = 2(18) + 12 + 48$

Answer:

1. $\text{Na}_2\text{SO}_4$: 142
2. $\text{H}_2\text{O}$: 18
3. $\text{CO}_2$: 44
4. $\text{Ca(OH)}_2$: 74
5. $\text{Al}_2(\text{SO}_4)_3$: 342
6. $\text{Mg}_3\text{N}_2$: 100
7. $\text{Sr(NO}_3\text{)}_2$: 212
8. $(\text{NH}_4)_2\text{CO}_3$: 96