A0.450 g sample of impure caco3(s) is dissolved in 50.0 ml of 0.150 m hcl ( aq ) . the equation for the reaction is caco3 ( s ) + 2 hcl ( aq ) ⟶ cacl2 ( aq ) + h2o ( l ) + co2 ( g ) the excess hcl ( aq ) is titrated by 5.35 ml of 0.125 m naoh ( aq ) . calculate the mass percentage of caco3(s) in the sample.

The mass percentage of CaCO3(s) in the sample is 83.4%

Explanation:

CaCO₃ + 2HCl  →  CaCl₂  +  H2O  +  CO₂

Let's find out the moles of each reactant:

[HCl] = 0.150 mol/L

Molarity . volume = moles

0.150 m/L . 0.050L = 7.5x10⁻³ moles HCl

Molar mass of CaCO₃ =100.08 g

Moles of CaCO₃ = Mass / Molar mass

0.450 g/100.08 g = 4.49x10⁻³ moles of salt

Ratio is 1:2

If 2 moles of HCl react with 1 mol of salt

7.5x10⁻³ moles of HCl react with 7.5x10⁻³ / 2 = 3.75x10⁻³ moles

We must find out the mass

Moles of CaCO₃ . Molar mass CO₃ = 0.3753 g

So now, the mass percentage of salt will be

0.450g ___ 100%

0.3753 g (0.3753 .100 )/0.450 =83.4 %

Molality → 0.188 m

Mole fraction of fructose → 0.00337

Mass percent of fructose in solution → 3.29 %

Molarity → 0.183 M

Explanation:

Solute → 34 g of fructose

Solvent → 1000 g of water

Solution → 1000 g of water + 34 g of fructose = 1034 g of solution.

We take account density to calculate, the solution's density

1.0078 g/mL = 1034 g / mL

1034 g / 1.0078 g/mL = 1026 mL

Molal concentration → moles of solute in 1kg of solvent

Moles of fructose = mass of fructose / molar mass

34 g/ 180g/mol = 0.188 mol

0.188 mol/1kg = 0.188 m

Mole fraction of fructose = Moles of fructose / Total moles

We determine the moles of water

Moles of water = 1000 g / 18 g = 55.5 mol

Total moles = moles of fructose + moles of water

0.188 mol + 55.5 mol = 55.743 mol

0.188 mol / 55.743 mol = 0.00337

Mass percent = mass of fructose in 100 g of solution

(Mass of fructose / Total mass ) . 100 = (34 g /1034 g) . 100 = 3.29 %

Molarity = Moles of solute in 1L of solution

We can also say mmol of solute in 1 mL of solution

0.188 mol of fructose = 188 mmol of fructose

Molarity = 188 mmol / 1026 mL of solution = 0.183 M