<h3>
#a.
Answer:</h3>
0.0063 mole
<h3>
Solution and explanation:</h3>
We are given 21.0 mL citric acid with a concentration of 0.30 M
Part a requires we calculate the number of moles of citric acid.
We need to know how to calculate the concentration of a solution;
Concentration or molarity = Number of moles ÷ Volume of the solution
Thus;
Number of moles = Concentration × Volume
Hence;
Moles = 0.30 M × 0.021 L
= 0.0063 mole
<h3>
#b. Answer</h3>
1.21 g citric acid
<h3>
Solution</h3>
Part B
We are required to calculate the mass of citric acid in the sample
Number of moles of a compound is calculated by dividing its mass by its molar mass.
Molar mass of Citric acid = 192.124 g/mol
Moles of citric acid = 0.0063 mole
But; Mass = Number of moles × Molar mass
Mass of citric acid = 0.0063 mol × 192.124 g/mol
= 1.21 g citric acid
<h3>#c. Answer</h3>
4.167 mL
<h3>Solution:</h3>
Part C
We are required to determine the initial volume before dilution;
We have;
Initial concentration (M1) = 0.30 M
Final volume (V2) = 250 mL or 0.25 L
Final concentration (M2) = 0.0050 M
Using the dilution formula we can get the initial volume;
Therefore, since; M1V1 =M2V2
V1 = M2V2÷M1
= (0.0050 × 0.25)÷ 0.30
= 0.004167 L or
= 4.167 mL
Therefore, the initial volume of the solution is 4.167 mL
