# Problems Regarding Organic Chemistry Reactions

A sample of ammonia has a mass of 56.6g. How many molecules are in this sample?

Please see attached.

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#### Solution Preview

I'll set up the questions for you. You do the math. That sound fair?

In all of these questions, the key is to set up the expression so that the units cancel out leaving you with the units you want for the answer.

1. (56.6 g)(1 mol/17.0 g)(6.023x10^23 molecules/mol) = x molecules

The 17.0 g/mol is the molar mass of NH3.

2. You determine the molar mass of NaHCO3 first. If you add them up you come to 84 g/mol. The three oxygen atoms add up to 48; therefore, the percentage of oxygen in NaHCO3 is:

48/84 x 100% = 57%

Therefore, 57% of 0.35 g is x grams.

3. Never, ever, ever change the formulas or the subscripts in the formulas!! Only change the number in front of the formula, i.e. the "coefficients."

4. First, find the molar mass of round up. It comes to 169 g/mol.

Therefore,

(1 mol/169 g)(500 g) = x moles

5. For this you have to calculate the percentage of ...

#### Solution Summary

The solution provides detailed steps to solving the questions related to organic chemistry reactions.