Question

The molecular weight of table salt, NaCI, is 58.8 g/mol. A tablespoon of salt weighs 6.37 grams. Calculate the number of moles of salt in one tablespoon.
Finally, solve (remember significant figures):
(equation in picture)

Answer 1

6.37/ 58.5= .108888889
Since it had 3 sig figs the answer is 0.109

Answer 2

Answer:

The number of moles of salt in one tablespoon is 0.108 moles.

Explanation:

The rule of three or is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them. That is, what is intended with it is to find the fourth term of a proportion knowing the other three. Remember that proportionality is a constant relationship or ratio between different magnitudes.

If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other) , the direct rule of three must be applied. To solve a direct rule of three, the following formula must be followed:

a → b

c → x

Then:

$x=\frac{c*b}{a}$

In this case the rule of three can be applied in the following way: if 58.8 g are contained in 1 mole, then 6.37 g in how many moles will they be contained?

$amount of moles=\frac{6.37 g*1mole}{58.8 g}$

amount of moles=  0.108 moles

The number of moles of salt in one tablespoon is 0.108 moles.