We are asked to determine the molecular formula of a compound with a molar mass of 34.2 g/mol and a percentage composition of 5.94% H. The compound is composed only of hydrogen and oxygen.
This means we need to do the following steps:
Step 1: Calculate the mass and moles of O and H in the compound.
Step 2: Determine the lowest whole number ratio of O and H to get the empirical formula.
Step 3: Get the ratio of the molar mass and empirical mass to determine the molecular formula.
Step 1: The compound is composed of O and H and we’re given the mass percent of H (5.94%). Recall that the mass percentages of a compound must add up to 100%.
Recall that mass percent is given by:
Assuming we have 100 g of the compound, this means we have 94.06 g O and 5.94 g H. Now, we need to get the moles of each element in the compound.
The atomic masses are 15.99 g/mol O and 1 g/mol H.
A compound composed of only hydrogen and oxygen is 5.94% hydrogen by mass. The molar mass of this compound is 34.02 g/mol. What is the compound's molecular formula?
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