Question

question 1
1 pts
calculate the percent by mass of hydrogen in methane, ch₄.
25.0%
25.1%
74.9%
20.0%
question 2
1 pts
calculate the percent composition of carbon in glucose, c₆h₁₂o₆.
40.0%
71.9%
53.3%
6.7%

Explanation:

Question 1

Step1: Calculate molar mass of \(CH_4\)

Molar mass of \(C = 12.01\space g/mol\), molar mass of \(H=1.008\space g/mol\).
Molar mass of \(CH_4=12.01+(4\times1.008)=12.01 + 4.032=16.042\space g/mol\)

Step2: Calculate mass of hydrogen in \(CH_4\)

Mass of \(H\) in \(CH_4 = 4\times1.008 = 4.032\space g/mol\)

Step3: Calculate mass percentage of \(H\)

Mass percentage of \(H=\frac{4.032}{16.042}\times100\%\approx25.1\%\)

Answer:

25.1%

Question 2

Step1: Calculate molar mass of \(C_6H_{12}O_6\)

Molar mass of \(C = 12.01\space g/mol\), molar mass of \(H = 1.008\space g/mol\), molar mass of \(O=16.00\space g/mol\)
Molar mass of \(C_6H_{12}O_6=(6\times12.01)+(12\times1.008)+(6\times16.00)=72.06+12.096 + 96.00=180.156\space g/mol\)

Step2: Calculate mass of carbon in \(C_6H_{12}O_6\)

Mass of \(C\) in \(C_6H_{12}O_6=6\times12.01 = 72.06\space g/mol\)

Step3: Calculate mass percentage of \(C\)

Mass percentage of \(C=\frac{72.06}{180.156}\times100\%\approx40.0\%\)