Astudent, wearing chemical safety goggles and a lab apron, is to perform a laboratory test to determine the ph value of two different solutions. the student is given one bottle containing a solution with a ph of 2.0 and another bottle containing a solution with a ph of 5.0. the student is also given six dropping bottles, each containing a different indicator listed in reference table m.
state one safety precaution, not mentioned in the passage, that the student should take while performing tests on the samples from the bottles.

the ratio of the conjugate base to the acid required to attain the desired ph.

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