To convert from the mass of a known compound to the mass of an unknown compound using stoichiometry, you will follow these logical steps to ensure proper calculations and minimize errors. The correct sequence should be as follows:
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Mass given from the problem of the known substance - Start with the mass of the known compound provided in the problem.
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Inverted molar mass of the known substance - Use the molar mass of the known substance to convert the mass into moles. (You will use the inverted value)
\[(\text{Mass of known}) \times \left(\frac{1 \text{ mol}}{\text{Molar mass of known}}\right)\]
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Mole ratio from the balanced equation of moles of unknown to moles of known - Use the mole ratio derived from the balanced chemical equation to convert moles of the known substance to moles of the unknown substance.
\[\text{Moles of known} \times \left(\frac{\text{Moles of unknown}}{\text{Moles of known}}\right)\]
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Molar mass of the unknown substance - Finally, convert moles of the unknown substance back into mass using its molar mass.
\[\text{Moles of unknown} \times \left(\text{Molar mass of unknown}\right)\]
In summary, the sequence is:
- Mass given from the problem of the known substance
- Inverted molar mass of the known substance
- Mole ratio from the balanced equation of moles of unknown to moles of known
- Molar mass of unknown substance
Following this order will help you correctly convert between the two compounds while minimizing potential errors.
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