6. a silver ring has a mass of 5.25 grams also. calculate the number of silver atoms present in the ring?
before you calculate, do you expect 5.25 grams of silver or gold to have more atoms?
7. a mercury thermometer breaks and spills 3.4 x 104 hg atoms all over the floor. calculate the mass of
mercury spilled on the floor?
8. 250.0 grams of silicon are massed on a scale. calculate how many silicon atoms are present in the
sample?

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