1) Percent composition
<span>Na: 13.60%,
N: 8.29%
C: 35.51%
H: 4.77%
O: 37.85%
-------------
100.02%
2) Convert mass percent to molar composition
For that, divide the percent of each element by its atomic mass.
</span>
<span>Na: 13.60 / 22.99 = 0.5916
N: 8.29 / 14.01 = 0.5917
C: 35.51 / 12.01 = 2.9567
H: 4.77 / 1.01 = 4.7228
O: 37.85 / 16.00 = 2.3656
3) Divide each number by the smallest one:
</span>
<span><span>Na: 0.5916 / 0.5916 = 1.0
N: 0.5917 / 0.5916 = 1.0
C: 2.9567 / 0.5916 = 5.0
H: 4.7228 / 0.5916 = 8.0
O: 2.3656</span> / 0.5916 = 4.0
4) State the empirical formula: Na N C5 H8 O4
5) Calculate the mass of the empirical formula:
Multiplicate the number of each atoms times the atomic mass corresponding atomic mass of the atom.
1 * 22.99 + 1 * 14.01 + 5 * 12.01 + 8 * 1.01 + 4 * 16.00 = 169.13
6) Divide the molar mass by the mass of the empirical formula:
169 / 169.13 = 1
7) Conclusion: the molecular formula is Na N C5 H8 O4, so the number of atoms present in the compound formula are:
Na: 1
N: 1
C: 5
N: 8
O: 4
</span>
Decomposition of stone due to acid rain<span />
Answer:
18.45 g of C
Explanation:
This is a problem of rules of three:
1 mol of C₃H₈ contains 3 moles of C and 8 moles of H
If 8 moles of H are contained in 1 mol of propane
4.10 moles of H are contained in (4.1 . 1) /8 = 0.5125 moles
Now, If 1 mol of propane contains 3 moles of C
0.5125 moles of propane may contain (0.5125 . 3) / 1 = 1.5375 moles of C
Let's convert the moles to mass:
1.5375 mol . 12 g /mol = 18.45 g
Answer:
300 mL
Explanation:
the unit formula of calcium phosphate is Ca3(PO4)2
molar mass of Ca3(PO4)2 = (3×40 + 2×31 + 8×16) g/mol = 310 g/mol
n = m/M = 35 g/(310 g/mol)
c = n/V
V = n/c = [35 g/(310 g/mol)]/0.375 mol/L
V = 0.30 L = 300 mL
