. A party-supply store sells a helium-gas cylinder with a volume a 0.0155 cubic meters. If the cylinder provides 1.81 cubic meters of helium for balloon inflation (at STP), what must be the pressure inside the cylinder

The pressure inside the cylinder is 8.6 × 10⁻³ atm

Explanation:

At STP, the pressure is 1 atm. As per the Boyle's law, if the temperature of a gas is kept constant then its volume and pressure are inversely proportional to each other. So P₁V₁= P₂V₂

Now we have to find the P₂ as

Inserting the given values, in the above expression, P1 = 1 atm, V1 = 0.0155 m³, V2 = 1.81 atm, P2 = ?, we will get P2 as,

P₂ = = 8.6 × 10⁻³ atm

So the pressure inside the cylinder is 8.6 × 10⁻³ atm

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.