Agraduated cylinder contains 15.75 ml of water. a metal that weighs 31.745 g is added. the final reading is 38.55 ml. using the correct number of significant figures, determine the density of the metal = g/ml first determine volume of metal: report result to the same number of decimal places as the number with the least number of decimal places. use this volume in calculation. second determine density of metal: d=m/v report result to the same number of significant figures as the number with the least number of significant figures. do not use exponential notation in answer.

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