1. You have 19.7 grams of a material and wonder how many moles were formed. Your
friend tells you to multiply the mass by grams/mole. Is your friend correct?
Hint Set in the solution an

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Answer:

No. If you were to set up what the friend said it would look like this:

19.7g × [tex]\frac{grams}{moles}[/tex] ==>  [tex]\frac{19.7 grams}{1}[/tex] ×

The above does not look right because the grams do not cancel out. If it's not cancelled, it would be included in your final answer, but you're looking for moles not grams.

When setting up a stoichiometry equation, you have to put the same unit of measurement (ex- grams, cm, mm, etc.) on the numerator of one side and the denominator of the other side.

This would cancel out the unit.

For example: If you wanted to find out how much of 320 cm are in a meter.

*there are 100 cm in 1 meter*

(1. always start with the given number!)

(2. set up the next fraction where you can cancel out cm)

[tex]\frac{320cm}{1}[/tex] × [tex]\frac{1 meter}{100 cm}[/tex] = 3.2 m

Going back, your friend would have to switch the units from grams/moles to moles/grams. It would cancel out grams, which would leave moles. Therefore, moles will be included in your final answer.

[tex]\frac{19.7 grams}{1}[/tex] × [tex]\frac{moles}{grams}[/tex] = _?_ moles

You will take the ratio of mass and molar mass. Hence my friend is wrong.

Number of moles and molar mass

The formula for calculating the number of moles is expressed as:

[tex]Moles=\frac{mass}{molar mass}[/tex]

Given the following

Mass = 19.7 grams

Since the molar mass is measured in gram per mole, hence to get the number of moles, you will take the ratio of mass and molar mass. Hence my friend is wrong.

Learn more on molar mass here: https://brainly.com/question/15476873

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