Question

3 SHOW ALL WORK STEP BY STEP WITHOUT SHORT CUTS

1) make a solution of 0.25% n-propanol (use 25 ml volumetric flask)

2) make a water solution of methanol and isopropanol of 0.2% make it in the same container and in separated container.

3) make a 50ml stock solution of 0.50 wt% ethanol .

4) make five solution ranging from of ethanol 0.0 %, 0.05%, 0.10%, 0.20,% 0.30% 0.40% 0.50% wt% in water. (Used 25ml volumetric flasks)

Answer 1

1). 0.25% n-propanol solution

0.25% n-propanol means: 0.25 mL n-propanol in 100 mL solution.

Volume of flask= 25 mL

So, maximum volume of solution = 25 mL

Volume of n-propanol required = 0.25/4 = 0.0625 mL

So, To make a 25 mL solution of  0.25% n-propanol, we need:

Volume of n-propanol = 0.0625 mL

Volume of water = 25 - 0.0625 = 24.9375 mL

2). water solution of methanol and isopropanol of 0.2%

0.2% means, 0.2 mL methanol and isopropanol in 100 mL solution.

When the solution is made in the same container:

Volume of methanol required = 0.2 mL

Volume of isopropanol required = 0.2 mL

Volume of water required = 100 - (0.2 + 0.2)

= 99.6 mL

When the solution is made in separated container.

Volume of methanol and isopropanol required = 0.2 mL each

Volume of water required = 99.8 mL for each container

3) make a 50ml stock solution of 0.50 wt% ethanol.

0.50 wt% ethanol means:

0.50 g ethanol is present in 100 g solution.

Mass of water used = 100 - 0.5 = 99.5 g

Volume of water = density * mass

= 1.0 * 99.5 = 99.5 mL

Mass of ethanol required for 50 mL water = 0.50/99.5 * 50

= 0.2512 g

So Weight of ethanol required = 0.2512 g

Volume of water required = 50 mL

4). For all the solutions volume of water required = 25 mL

For 0.0% ethanol solution

Mass of ethanol required = 0g

For 0.05% ethanol solution:

Mass of ethanol required = 0.05 / 99.95 * 25

= 0.0125 g

For 0.10% ethanol solution:

Mass of ethanol required = 0.10 / 99.9 * 25

= 0.025 g

For 0.20% ethanol solution:

Mass of ethanol required = 0.20 / 99.8 * 25

= 0.050 g

For 0.30% ethanol solution:

Mass of ethanol required = 0.30 / 99.7 * 25

= 0.0752 g

For 0.40% ethanol solution:

Mass of ethanol required = 0.40 / 99.6 * 25

= 0.100 g

For 0.50% ethanol solution:

Mass of ethanol required = 0.50 / 99.5 * 25

= 0.1256 g