Calcium hydride (CaH2) reacts with water to form hydrogen gas: CaH2(s) + 2 H2O(l) → Ca(OH)2(aq) + 2 H2(g) Determine the number of grams of CaH2 are needed to generate 55.0 L of H2 gas at a pressure of 0.811 atm and a temperature of 32°C.\

Explanation:

Hello,

In this case, since the undergoing chemical reaction is:

By knowing the gas data of hydrogen, we can compute the formed moles by considering the ideal gas equation as:

In such a way, since hydrogen and calcium hydride have a 2 to 1 molar relationship in the chemical reaction, the number of grams of calcium hydride turns out, by means of stoichiometry:

Best regards.

m = 37.5373 g

Explanation:

To do this, let's write the reaction again:

CaH₂(s) + 2H₂O(l) > Ca(OH)₂(aq) + 2H₂(g)

In this reaction we can see that the mole ratio of CaH₂ and H₂ is 1:2, in other words:

moles CaH₂/moles H₂ = 1/2

We need to know how many grams of CaH₂ reacted to form 55 L of Hydrogen. to do this, we need to know how many moles of Hydrogen were produced. and as Hydrogen is a gas, and we know the volume and pressure of it, we can use the ideal gas equation to solve for the moles of hydrogen:

PV = nRT      solvinf for the moles:

n = PV / RT

R is constant of gases and is 0.082 L atm /mol K and the temperature is 32 °C (305 K) so, the moles are:

n = 0.811 * 55 / 0.082 * 305

n = 1.7835 moles

We have the moles, let's calculate the moles of CaH₂ used with the mole ratio of before:

moles CaH₂/moles H₂ = 1/2

moles CaH₂ = moles H₂/2

moles CaH₂ = 1.78 / 2 = 0.89175 moles

Finally the mass is calculated using the molecular mass of CaH₂ which is 42.094 g/mol, so the mass is:

m = 0.89175 * 42.094

a c d and f

just finished the assignment

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.