Justin mixed two clear liquids together during an experiment and made the following observations: the mixed liquids decreased in temperature without any refrigeration or other action to change the temperature. the color of the liquid changed to blue. which statement best describes justin’s experiment? a. a physical change occurred, and this caused the liquid’s chemical properties to change. b. a chemical change occurred, and this caused the liquid’s physical properties to change. c. a physical change occurred, so only physical properties changed. d. a chemical change occurred, so only chemical properties changed.

B

Explanation:

A chemical change occurred, and this caused the liquid’s physical properties to change.

when we read her experiment we can see that color changed to blue, it is because new products are formed. And the temperature cause this.

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