Question

1. A solution contains 0.75 mols of HCl in 400.0 mL. What is its molarity?

2. How many grams of CaCl2 are needed to make 350.0 mL of a 1.5 M solution?
3. What is the molarity of a 750.0 mL solution made by diluting 250.0 mL of 12 M HCl?
4. How much water was added in #3?

Answer 1

Step-by-step explanation:

Molarity (M) is calculated by dividing moles of solute by liters of solution. In this case,

�

=

0.75

mol

0.4

L

M=

0.4 L

0.75 mol

.

To find the grams of CaCl2, use the formula:

grams

=

moles

×

molar mass

grams=moles×molar mass. First, calculate moles using

moles

=

Molarity

×

volume (L)

moles=Molarity×volume (L).

Dilution formula is

�

1

�

1

=

�

2

�

2

M

1

V

1

=M

2

V

2

. Plug in the values:

(

12

M

)

(

0.25

L

)

=

�

2

(

0.75

L

)

(12 M)(0.25 L)=M

2

(0.75 L) to find the molarity of the diluted solution.

The added water is the difference in volumes:

Final volume

−

Initial volume

Final volume−Initial volume.

0.75

L

−

0.25

L

0.75 L−0.25 L.