1. How many grams of NaOH will be needed to prepare 250 ml of 0.1M solution? (Na=23, O=16, H=1). 2. The density of 95.2% of H2SO4 is 1.53 g/ml. Calculate the molarity of this solut... 1. How many grams of NaOH will be needed to prepare 250 ml of 0.1M solution? (Na=23, O=16, H=1). 2. The density of 95.2% of H2SO4 is 1.53 g/ml. Calculate the molarity of this solution (M.Wt. = 98). 3. Calculate the volume of conc. H2SO4 (97% weight percent, density 1.84 g/ml) required to prepare 500 ml of 1.25N solution (M.Wt.= 98). 4. Calculate the normality of a solution prepared by adding 7.1 g of Na2SO4 to water to make 100 ml of solution. Read more

Steps to Solve

1. Calculate grams of NaOH for 0.1 M solution

To find the grams of NaOH needed to prepare 250 ml of a 0.1 M solution, use the formula: $$ \text{Molarity (M)} = \frac{\text{moles of solute}}{\text{liters of solution}} $$

First, convert 250 ml to liters: $$ 250 , \text{ml} = 0.250 , \text{L} $$

Next, calculate moles required: $$ \text{Moles of NaOH} = 0.1 , \text{M} \times 0.250 , \text{L} = 0.025 , \text{moles} $$

Now convert moles to grams using the molar mass of NaOH (Na = 23, O = 16, H = 1): $$ \text{Molar mass of NaOH} = 23 + 16 + 1 = 40 , \text{g/mol} $$

Calculate grams: $$ \text{Grams of NaOH} = 0.025 , \text{moles} \times 40 , \text{g/mol} = 1.0 , \text{g} $$

2. Calculate molarity of H₂SO₄ solution

Given the density of the H₂SO₄ solution (95.2% by weight) and its density (1.53 g/ml), calculate its molarity.

First, find the mass of the 1 liter of solution: $$ \text{Mass of solution} = 1 , \text{L} \times 1.53 , \text{g/ml} \times 1000 , \text{ml} = 1530 , \text{g} $$

Now find the mass of H₂SO₄ in the solution: $$ \text{Mass of H₂SO₄} = 0.952 \times 1530 , \text{g} = 1457.76 , \text{g} $$

Now convert grams to moles: $$ \text{Moles of H₂SO₄} = \frac{1457.76 , \text{g}}{98 , \text{g/mol}} \approx 14.85 , \text{moles} $$

Calculate molarity: $$ \text{Molarity} = \frac{14.85 , \text{moles}}{1 , \text{L}} = 14.85 , \text{M} $$

3. Calculate volume of concentrated H₂SO₄ for 1.25N solution

For a 1.25 N solution, find the volume of concentrated H₂SO₄ needed.

Knowing that:

• Molarity = Normality for diprotic acids (like H₂SO₄)

Using the equation: $$ \text{Normality} = \frac{\text{grams of solute}}{\text{Volume of solution (liters)} \times \text{Equivalent weight}} $$

Calculate grams of H₂SO₄ required for 500 ml of solution: $$ \text{Grams required} = 1.25 \times 0.5 \times 98 \approx 61.25 , \text{grams} $$

Calculate volume needed from the concentrated solution using density: $$ \text{Volume} = \frac{\text{mass}}{\text{density}} = \frac{61.25 , \text{g}}{1.84 , \text{g/ml}} \approx 33.33 , \text{ml} $$

4. Calculate normality of Na₂SO₄ solution

For a solution made by dissolving 7.1 g of Na₂SO₄ in water to make 100 ml:

• Molar mass of Na₂SO₄ = 2(23) + 32 + 4(16) = 142 g/mol

Find moles: $$ \text{Moles of Na₂SO₄} = \frac{7.1}{142} \approx 0.050 , \text{moles} $$

Since Na₂SO₄ provides 2 equivalents (as a diprotic salt): Normality is calculated as: $$ \text{Normality} = \frac{\text{equivalents}}{\text{volume (L)}} = \frac{0.050 \times 2}{0.1} = 1.0N $$