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3 years ago

How many moles of NaCl are in 75.0 g of NaCl ?

2 answers:

6 0

Number of moles is found by formula n=mass/molar mass, or m/M. the molar mass is found by adding together the atomic masses of Na and Cl (22.99 + 35.45) to give 58.44 g/mol. Since the mass of NaCl is 75.0g, we find the number of moles as follows:
n = 75.0 / 58.44 = 1.28 mol

Mkey [24]3 years ago

6 0

To find the number of moles of any compound you should divide the mass over the molar mass of that compound

<span>so for your question, </span>

<span>number of moles = mass/ molar mass </span>
<span>= 75.0 g / 58.443 g/mol </span>
<span>= 1.2833 </span>
<span>= 1.28 and note that the answer is rounded to 3 significant figures</span>

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3 years ago

A sample of an unknown compound has a percent composition of 52.14% carbon, 13.13% hydrogen, and 34.73% oxygen. Which compounds

Artemon [7]

<h3>Answer:</h3>

The two possible compounds are;

1) Dimethyl Ether H₃C--O--CH₃

2) Ethanol H₃C--CH₂--OH

<h3>Solution:</h3>

Step 1: Calculate Moles of each Element;

Moles of C = %C ÷ At.Mass of C

Moles of C = 52.14 ÷ 12.01

Moles of C = 4.341 mol

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Step 2: Find out mole ratio and simplify it;

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4.341 13.00 2.170

4.341/2.170 13.00/2.170 2.170/2.170

2 5.99 1

2 6 1

Hence, Empirical Formula = C₂H₆O

<h3>Result:</h3>

As the molecular mass of compound is not given therefore, we can assume and guess the empirical formula to be the molecular formula. Hence, possible compounds are,

1) Dimethyl Ether H₃C--O--CH₃

2) Ethanol H₃C--CH₂--OH

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3 years ago