Question

When 50. Ml of 10% (m/v) NaCl is diluted to 500. mL the NaCl concentration is ____%

Answer 1

To calculate the NaCl concentration when a 50 mL of 10% (m/v) NaCl solution is diluted to 500 mL, use the formula for percentages and volume ratios. The NaCl concentration is 1%.

Step-by-step explanation:

To determine the NaCl concentration when a 50 mL of 10% (m/v) NaCl solution is diluted to 500 mL, we can use the formula for calculating percentages:

Percentage (%) = (Amount of solute / Amount of solution) × 100%

First, we need to calculate the amount of NaCl in the original solution:

Amount of NaCl = 10% × 50 mL = 5 mL

Then, we can use the diluted volume to find the new concentration:

NaCl concentration = (Amount of NaCl / Total volume of solution) × 100%

= (5 mL / 500 mL) × 100%

= 1% NaCl

Answer 2

= 0.01 % m/v

Step-by-step explanation:

From the information given we first need to understand the meaning of;

10% m/v, it means 10% mass to volume ratio

That is; 10g of a solute (NaCl) are present in 100 mL of solution (water)

Therefore;

First, we can determine the concentration of the initial solution of NaCl

Concentration = Moles ÷ Volume

But, Moles = Mass ÷ Molar mass

Molar mass of NaCl = 58.44 g/mol

Moles = 10 g ÷ 58.44 g/mol

= 0.171 moles

Thus;

Concentration= 0.171 moles × 0.1 L

= 0.0171 M

Second, we can determine the concentration of the solution after dilution.

Using dilution equation;

M1V1 = M2V2

M2 = M1V1 ÷ V2

= (0.0171 M×0.05 L) ÷ 0.5 L

= 0.00171 M

Therefore, the concentration after dilution is 0.00171 M

Thirdly, we find the % by mass to volume ratio

Concentration = 0.00171 M ( means 0.00171 moles/liter)

Mass of NaCl = 0.00171 moles × 58.44 g/mol

= 0.09993

= 0.1 g

0.1 g = 1000 mL(1 L) (0.1 g/L)

To get % m/v we find the Mass in 100 mL will be;

= (0.1 g× 100 mL)÷ 1000 mL

= 0.01 % m/v