Ethane (C2H6) burns with oxygen to produce carbon dioxide and water. A sample of ethane was burned completely and the water that formed had a mass of 1.61g. How much ethane, in moles and in grams, was in the sample?
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To determine the amount of ethane in moles and grams, we need to use the concept of stoichiometry and the balanced chemical equation for the combustion of ethane.
The balanced equation is:
C2H6 + 7/2 O2 -> 2 CO2 + 3 H2O
From the equation, we can see that 1 mole of ethane reacts with 3 moles of water. We are given the mass of water produced, which is 1.61g.
Step 1: Convert mass of water to moles
To convert the mass of water to moles, we need to know the molar mass of water (H2O). The molar mass of H2O is approximately 18.015 g/mol.
Therefore, the number of moles of water produced is:
moles of water = mass of water / molar mass of water
= 1.61g / 18.015 g/mol
≈ 0.0894 mol (rounded to four decimal places)
Step 2: Determine moles of ethane
From the balanced equation, we know that 1 mole of ethane reacts with 3 moles of water. Therefore, the number of moles of ethane can be determined by multiplying the moles of water by the ratio of the coefficients between ethane and water.
moles of ethane = moles of water * (1 mole of ethane / 3 moles of water)
= 0.0894 mol * (1/3)
= 0.0298 mol (rounded to four decimal places)
Step 3: Convert moles of ethane to grams
To convert the moles of ethane to grams, we need to know the molar mass of ethane (C2H6). The molar mass of C2H6 is approximately 30.07 g/mol.
Therefore, the mass of ethane is:
mass of ethane = moles of ethane * molar mass of ethane
= 0.0298 mol * 30.07 g/mol
≈ 0.895 g (rounded to three decimal places)
Therefore, the sample of ethane in the combustion had approximately 0.0298 moles and 0.895 grams.