A chemist wants to increase the solubility of a chemical in water. Which of the following WILL NOT help?
a) Increase the temperature
b) Decrease the particle size
c) Increase stirring
d) Increase pressure

Increase pressure

Explanation:

Liquids and solids exhibit practically no change of solubility with changes in pressure. Gases as might be expected, increase in solubility with an increase in pressure. This is typified by Henry's law. Henry's Law states that: The solubility of a gas in a liquid is directly proportional to the pressure of that gas above the surface of the solution.

Temperature affects the solubility of both solids and gases, but pressure only affects the solubility of gases. Surface area does not affect how much of a solute will be dissolved, but it is a factor in how quickly or slowly the substance will dissolve.

The solubility of a solid may increase or decrease with increasing temperature, whereas the solubility of a gas decreases with an increase in temperature and a decrease in pressure.

Since the chemical referred to in the question can not be a gas, then increase in pressure will not affect its solubility.

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