Question

Calculate the Molarity of the solution containing 18.4g of Pottasium Carbonate dissolve in 250ml of solution? ​

Answer 1

Answer:

Explanation:

0.76 mol L

−

1

Explanation:

I would say that you're dealing with a solution that contains  

14.2

grams of potassium chloride,  

KCl

, in  

250 mL

of solution.

If this is the case, your strategy here will be to use the molar mass of potassium chloride to calculate how many moles are present in the sample

14.2

g

⋅

1 mole KCl

74.55

g

=

0.1905 moles KCl

Now, molarity is simply a measure of a solution's concentration in terms of how many moles of solute it contains per liter of solution.

This means that in order to find a solution's molarity, you essentially must figure out how many moles of solute you have in  

1 L

of solution.

In your case, you know that  

250 mL

, which is equivalent to  

1

4

th

of a liter, contains  

0.905

moles.

All you have to do now is scale up this solution so that its volume becomes  

1 L

. Simply put, if  

1

4

th

of a liter contains  

0.1905

moles, it follows that  

1 L

will contain four times as many moles of solute.

1

L solution

⋅

0.905 moles KCl

1

4

L solution

=

0.76 moles KCl

So, if  

1 L

of this solution contains  

0.76

moles of solute, it follows that its molarity is

molarity

=

∣

∣

∣

∣

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

a

a

0.76 mol L

−

1

a

a

∣

∣

−−−−−−−−−−−−−−−−

 

The answer is rounded to two sig figs, the number of sig figs you have for the volume of the solution.