A) covert 0.330g to moles by dividing by molar mass of P2O5 .. Let's call this Y moles
B) 1 mole of anything contains the Avogradro Number of molecules
So here it is 6.02 x 10^23 x Y molecules
C) work out how many atoms in each molecule 2P + 5O total 7
So multiply answer to B by 7 to get final answer
Answer:
1. 8.7moles of H2
2. 2.25moles of O2
Explanation:
1. 2NH3 —> N2 + 3H2
From the equation,
2moles of NH3 produce 3 moles of H2.
Therefore, 5.8moles of NH3 will produce Xmol of H2 i.e
Xmol of H2 = (5.8x3)/2 = 8.7moles
2. C3H8 + 5O2 —> 3CO2 + 4H2O
From the equation,
5moles of O2 produced 4moles of H2O.
Therefore, Xmol of O2 will produce 1.8mol of H2O i.e
Xmol of O2 = (5x1.8)/4 = 2.25moles
Since it’s asking for chemical to thermal, B.
The much of the sample that would remain unchanged after 140 seconds is 2.813 g
Explanation
Half life is time taken for the quantity to reduce to half its original value.
if the half life for Scandium is 35 sec, then the number of half life in 140 seconds
=140 sec/ 35 s = 4 half life
Therefore 45 g after first half life = 45 x1/2 =22.5 g
22.5 g after second half life = 22.5 x 1/2 =11.25 g
11.25 g after third half life = 11.25 x 1/2 = 5.625 g
5.625 after fourth half life = 5.625 x 1/2 = 2.813
therefore 2.813 g of Scandium 47 remains unchanged.
Answer : The internal energy change is, -506.3 kJ/mol
Explanation :
Formula used :
or,
where,
= change in enthalpy = 
= change in internal energy = ?
= change in moles
Change in moles = Number of moles of product side - Number of moles of reactant side
According to the reaction:
Change in moles = 0 - 2 = -2 mole
That means, value of 
= 0
R = gas constant = 8.314 J/mol.K
T = temperature = 
Now put all the given values in the above formula, we get
Therefore, the internal energy change is -506.3 kJ/mol
