Answer:
ΔH = -976.5 kJ
Explanation:
For the reaction given, there are 2 moles of benzene (C6H6). The heat of this reaction is -6278 kJ, which means that the combustion of 2 moles of benzene will lose 6278 kJ of heat. It is an exothermic reaction.
The value of ΔH, the enthalpy, is a way of measurement of the heat, and it depends on the quantity of the matter (number of moles).
So, 24.3 g of benzene has :
n = mass/ molar mass
n = 24.3/78.11
n = 0.311 moles
2 moles ------------ -6278 kJ
0.311 moles ----------- x
By a simple direct three rule:
2x = -1953.08
x = -976.5 kJ
Answer is: volume of helium is 244.72 liters.
m(He) = 43.7 g.
n(He) = m(He) ÷ M(He).
n(He) = 43.7 g ÷ 4 g/mol.
n(He) = 10.925 mol.
V(He) = n(He) · n(He).
V(He) = 10.925 mol · 22.4 L/mol.
V(He) = 244.72 L.
Vm - molar volume at STP.
n - amount of substance.
A strong electrolyte like MgCl2 dissociates completely as per the following reaction:
As you can see, from 1 molecule of MgCl2 produces 3 ions on dissociation.
So, 1 mole of MgCl2 produces 3 moles of ions.
Now, Moles of MgCl2 = Volume x Molarity
= 0.04 x 0.345 [Change volume to Litres]
= 0.0138 moles
Now, total moles of ions = 0.0138 x 3 = 0.0414
The equilibrium constant Kc for this reaction is calculated as follows
from the equation N2 + 3H2 =2 NH3
qc = (NH3)2/{(N2)(H2)^3}
Qc is therefore = ( 0.001)2 /{(0.1) (0.05)^3} = 0.08
Answer:
3.52g
Explanation:
Zr = 90 g/mol
Si = 28 g/mol
O = 16 g/mol
ZrSiO4 = 90 + 28 + (16* 4) = 182g/mol
Mass = Numberof moles * Molar mass
Mass = 1mol * 182g/mol = 182g
In one mole of ZrSiO4, there are 4 oxygen atoms, hence the mass is given as;
4 * 16 = 64g
Hence, 64g of oxygen is present in 182g of ZrSiO4.
10g would contain x
64 = 182
x = 10
x = ( 10 * 64 ) / 182
x = 640 / 182 = 3.52g
