Aluminum has a density of 2.70 g/cm3. if you have a volume of 275 cm3, what is the mass in kilograms

Density is defined as the ratio of mass to the volume.

The mathematical expression is given as:

where, d = density

m = mass and v= volume

Plug in the value of density i.e. and volume i.e.  in above formula;

Now from conversion factors, 1 kg = 1000 g

Thus, mass of aluminium in kg  =

=

Hence, mass of aluminium in kg =

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