Question

chapter 3 review worksheet
name:

1. what is the mass of 5 moles of fe₂o₃?
2. find the number of moles of argon in 452 g of argon.
3. determine the number of molecules of 14 g of nitrogen dioxide (no₂).
4. find the mass, in grams, of 1.00×10²³ molecules of n₂.
5. how many moles of magnesium are in 3.01×10²² atoms of magnesium?
6. how many molecules are there in 4.00 moles of glucose, c₆h₁₂o₆?

Explanation:

Step1: Calculate molar mass of \(Fe_2O_3\)

Molar mass of \(Fe = 55.85\space g/mol\), molar mass of \(O = 16.00\space g/mol\).
Molar mass of \(Fe_2O_3=2\times55.85 + 3\times16.00=111.7+48 = 159.7\space g/mol\)

Step2: Calculate mass of 5 moles of \(Fe_2O_3\)

Using formula \(m=n\times M\) (where \(m\) is mass, \(n\) is number of moles, \(M\) is molar mass)
\(m = 5\times159.7=798.5\space g\)

Step3: Calculate molar mass of argon

Molar mass of \(Ar = 39.95\space g/mol\)

Step4: Calculate number of moles of argon

Using formula \(n=\frac{m}{M}\) (where \(m = 452\space g\), \(M = 39.95\space g/mol\))
\(n=\frac{452}{39.95}\approx11.3\space mol\)

Step5: Calculate molar mass of \(NO_2\)

Molar mass of \(N = 14.01\space g/mol\), molar mass of \(O = 16.00\space g/mol\)
Molar mass of \(NO_2=14.01+2\times16.00 = 14.01 + 32=46.01\space g/mol\)

Step6: Calculate number of moles of \(NO_2\)

Using formula \(n=\frac{m}{M}\) (where \(m = 14\space g\), \(M = 46.01\space g/mol\))
\(n=\frac{14}{46.01}\approx0.304\space mol\)

Step7: Calculate number of molecules of \(NO_2\)

Using formula \(N=n\times N_A\) (\(N_A = 6.022\times10^{23}\space mol^{-1}\))
\(N=0.304\times6.022\times10^{23}\approx1.83\times10^{23}\)

Step8: Calculate molar mass of \(N_2\)

Molar mass of \(N = 14.01\space g/mol\), molar mass of \(N_2=2\times14.01 = 28.02\space g/mol\)

Step9: Calculate number of moles of \(N_2\)

Using formula \(n=\frac{N}{N_A}\) (where \(N = 1.00\times10^{23}\), \(N_A = 6.022\times10^{23}\space mol^{-1}\))
\(n=\frac{1.00\times10^{23}}{6.022\times10^{23}}\approx0.166\space mol\)

Step10: Calculate mass of \(N_2\)

Using formula \(m=n\times M\) (\(M = 28.02\space g/mol\), \(n\approx0.166\space mol\))
\(m=0.166\times28.02\approx4.65\space g\)

Step11: Calculate number of moles of magnesium

Using formula \(n=\frac{N}{N_A}\) (where \(N = 3.01\times10^{22}\), \(N_A = 6.022\times10^{23}\space mol^{-1}\))
\(n=\frac{3.01\times10^{22}}{6.022\times10^{23}}\approx0.05\space mol\)

Step12: Calculate number of molecules of glucose

Using formula \(N=n\times N_A\) (\(n = 4.00\space mol\), \(N_A = 6.022\times10^{23}\space mol^{-1}\))
\(N=4.00\times6.022\times10^{23}=2.41\times10^{24}\)

Answer:

1. \(798.5\space g\)
2. \(11.3\space mol\)
3. \(1.83\times10^{23}\)
4. \(4.65\space g\)
5. \(0.05\space mol\)
6. \(2.41\times10^{24}\)