A chemist prepares a solution of potassium dichromate by measuring out of potassium dichromate into a volumetric flask and filling the flask to the mark with water. Calculate the concentration in of the chemist's potassium dichromate solution. Be sure your answer has the correct number of significant digits.

0.297 mol/L

Explanation:

A chemist prepares a solution of potassium dichromate by measuring out 13.1 g of potassium dichromate into a 150 mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in mol/L of the chemist's potassium dichromate solution. Be sure your answer has the correct number of significant digits.

Step 1: Calculate the moles corresponding to 13.1 g of potassium dichromate

The molar mass of potassium dichromate is 294.19 g/mol.

13.1 g × (1 mol/294.19 g) = 0.0445 mol

Step 2: Convert the volume of solution to L

We will use the relationship 1 L = 1000 mL.

150 mL × (1 L/1000 mL) = 0.150 L

Step 3: Calculate the concentration of the solution in mol/L

C = 0.0445 mol/0.150 L = 0.297 mol/L

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2