Answer:
39.3%
Explanation:
CaF2 + H2SO4 --> CaSO4 + 2HF
We must first determine the limiting reactant, the limiting reactant is the reactant that yields the least number of moles of products. The question explicitly says that H2SO4 is in excess so CaF2 is the limiting reactant hence:
For CaF2;
Number of moles reacted= mass/molar mass
Molar mass of CaF2= 78.07 g/mol
Number of moles reacted= 11g/78.07 g/mol = 0.14 moles of Calcium flouride
Since 1 mole of calcium fluoride yields two moles of 2 moles hydrogen fluoride
0.14 moles of calcium fluoride will yield 0.14×2= 0.28 moles of hydrogen fluoride
Mass of hydrogen fluoride formed (theoretical yield) = number of moles× molar mass
Molar mass of hydrogen fluoride= 20.01 g/mol
Mass of HF= 0.28 moles × 20.01 g/mol= 5.6 g ( theoretical yield of HF)
Actual yield of HF was given in the question as 2.2g
% yield of HF= actual yield/ theoretical yield ×100
%yield of HF= 2.2/5.6 ×100
% yield of HF= 39.3%
Answer:
Option A; V = 2.92 L
Explanation:
If we assume a lot of things, like:
The gas is an ideal gas.
The temperature is constant.
The gas does not interchange mass with the environment.
Then we have the relation:
P*V = n*R*T = constant.
Where:
P = pressure
V = volume
n = number of moles
R = constant of the ideal gas
T = temperature.
We know that when P = 0.55 atm, the volume is 5.31 L
Then:
(0.55 atm)*(5.31 L) = constant
Now, when the gas is at standard pressure ( P = 1 atm)
We still have the relation:
P*V = constant = (0.55 atm)*(5.31 L)
(1 atm)*V = (0.55 atm)*(5.31 L)
Now we only need to solve this for V.
V = (0.55 atm/ 1 atm)*(5.31 L) = 2.92 L
V = 2.92 L
Then the correct option is A.
In this question, you are given the gasoline density (0.749g/ml) and volume of the gasoline (19.2 gallons). You are asked the mass of the gasoline in pounds. Then you need to change the grams into pounds and the ml into gallons. The calculation would be:
mass of gasoline= density * volume
mass of gasoline= 0.749g/ml * (1 pound/453.592grams) * 3785.41ml/gallon * 19.2 gallon= 120 pounds
A system of government by the whole population or all the eligible members of a state, typically through elected representatives.
"a system of parliamentary democracy"
a state governed under a system of democracy.
plural noun: democracies
"a multiparty democracy"
control of an organization or group by the majority of its members.
"the intended extension of industrial democracy"
