Question

homework: moles & mass
convert to moles (show all work & units to receive full credit.)

1. 100 g kmno4
2. 74 g potassium chloride
3. 35 g copper (ii) sulfate

convert to grams (show all work & units to receive full credit.)

1. 1.7 moles of kmno4
2. 0.25 moles of potassium chloride
3. 3.2 moles of copper (ii) sulfate

solve the following (show all work & units to receive full credit.)

1. how many moles of nacl are in 16.0 grams of nacl?
2. how many grams of glucose, c6h12o6, are there in 4.67 moles of glucose?

Explanation:

Step1: Calculate molar mass of \(KMnO_4\)

Molar mass of \(K = 39.1\space g/mol\), \(Mn = 54.9\space g/mol\), \(O = 16.0\space g/mol\).
Molar mass of \(KMnO_4=39.1 + 54.9+(4\times16.0)=158.0\space g/mol\)
Moles \(n=\frac{m}{M}\), where \(m = 100\space g\), \(M = 158.0\space g/mol\)
\(n=\frac{100\space g}{158.0\space g/mol}\approx0.633\space mol\)

Step2: Calculate molar mass of \(KCl\)

Molar mass of \(K = 39.1\space g/mol\), \(Cl = 35.5\space g/mol\)
Molar mass of \(KCl=39.1 + 35.5 = 74.6\space g/mol\)
Moles \(n=\frac{m}{M}\), where \(m = 74\space g\), \(M = 74.6\space g/mol\)
\(n=\frac{74\space g}{74.6\space g/mol}\approx0.992\space mol\)

Step3: Calculate molar mass of \(CuSO_4\)

Molar mass of \(Cu = 63.5\space g/mol\), \(S = 32.1\space g/mol\), \(O = 16.0\space g/mol\)
Molar mass of \(CuSO_4=63.5+32.1+(4\times16.0)=159.6\space g/mol\)
Moles \(n=\frac{m}{M}\), where \(m = 35\space g\), \(M = 159.6\space g/mol\)
\(n=\frac{35\space g}{159.6\space g/mol}\approx0.219\space mol\)

Step4: Calculate molar mass of \(KMnO_4\) (already calculated as \(158.0\space g/mol\))

Mass \(m=n\times M\), where \(n = 1.7\space mol\), \(M = 158.0\space g/mol\)
\(m=1.7\space mol\times158.0\space g/mol = 268.6\space g\)

Step5: Calculate molar mass of \(KCl\) (already calculated as \(74.6\space g/mol\))

Mass \(m=n\times M\), where \(n = 0.25\space mol\), \(M = 74.6\space g/mol\)
\(m=0.25\space mol\times74.6\space g/mol = 18.65\space g\)

Step6: Calculate molar mass of \(CuSO_4\) (already calculated as \(159.6\space g/mol\))

Mass \(m=n\times M\), where \(n = 3.2\space mol\), \(M = 159.6\space g/mol\)
\(m=3.2\space mol\times159.6\space g/mol = 510.72\space g\)

Step7: Calculate molar mass of \(NaCl\)

Molar mass of \(Na = 22.99\space g/mol\), \(Cl = 35.5\space g/mol\)
Molar mass of \(NaCl=22.99+35.5 = 58.49\space g/mol\)
Moles \(n=\frac{m}{M}\), where \(m = 16.0\space g\), \(M = 58.49\space g/mol\)
\(n=\frac{16.0\space g}{58.49\space g/mol}\approx0.274\space mol\)

Step8: Calculate molar mass of \(C_6H_{12}O_6\)

Molar mass of \(C = 12.01\space g/mol\), \(H = 1.01\space g/mol\), \(O = 16.0\space g/mol\)
Molar mass of \(C_6H_{12}O_6=(6\times12.01)+(12\times1.01)+(6\times16.0)=180.18\space g/mol\)
Mass \(m=n\times M\), where \(n = 4.67\space mol\), \(M = 180.18\space g/mol\)
\(m=4.67\space mol\times180.18\space g/mol\approx841.44\space g\)

Answer:

1. \(0.633\space mol\)
2. \(0.992\space mol\)
3. \(0.219\space mol\)
4. \(268.6\space g\)
5. \(18.65\space g\)
6. \(510.72\space g\)
7. \(0.274\space mol\)
8. \(841.44\space g\)