Respuesta :
Answer: The mass of unknown acid needed is 0.230 grams
Explanation:
To calculate the number of moles for given molarity, we use the equation:
[tex]\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}[/tex]
Molarity of NaOH solution = 0.100 M
Volume of solution = 15.00 mL = 0.015 L (Conversion factor: 1 L = 1000 mL)
Putting values in above equation, we get:
[tex]0.100M=\frac{\text{Moles of NaOH}}{0.015L}\\\\\text{Moles of NaOH}=(0.100mol/L\times 0.015L)=0.0015mol[/tex]
The chemical reaction for the reaction of KHP and NaOH follows
[tex]KHC_8H_4O_4(aq.)+NaOH\rightarrow KNaC_8H_4O_4(aq.)+H_2O(l)[/tex]
By Stoichiometry of the reaction:
1 mole of NaOH reacts with 1 mole of KHP.
So, 0.0015 moles of NaOH will react with = [tex]\frac{1}{1}\times 0.0015=0.0015mol[/tex] of KHP
- To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
Moles of KHP = 0.0015 moles
Molar mass of KHP = 204.22 g/mol
Putting values in above equation, we get:
[tex]0.0015mol=\frac{\text{Mass of KHP}}{204.22g/mol}\\\\\text{Mass of KHP}=(0.0015mol\times 204.22g/mol)=0.306g[/tex]
We are given:
Mass of unknown acid = 75 % of Mass of KHP
So, mass of unknown acid = [tex]\frac{75}{100}\times 0.306=0.230g[/tex]
Hence, the mass of unknown acid needed is 0.230 grams
