Answer:
1. Percentage by weight = 0.5023 = 50.23 %
2. molar fraction =0.153
Explanation:
We know that
Molar mass of HClO4 = 100.46 g/mol
So the mass of 5 Moles= 5 x 100.46
Mass (m)= 5 x 100.46 = 502.3 g
Lets assume that aqueous solution of HClO4 and the density of solution is equal to density of water.
Given that concentration HClO4 is 5 M it means that it have 5 moles of HClO4 in 1000 ml.
We know that
Mass = density x volume
Mass of 1000 ml solution = 1 x 1000 =1000 ( density = 1 gm/ml)
m'=1000 g
1.
Percentage by weight = 502.3 /1000
Percentage by weight = 0.5023 = 50.23 %
2.
We know that
molar mass of water = 18 g/mol
mass of water in 1000 ml = 1000 - 502.3 g=497.9 g
So moles of water = 497.7 /18 mole
moles of water = 27.65 moles
So molar fraction = 5/(5+27.65)
molar fraction =0.153
Lar mass of Ca<span> = 40.08 </span>grams/mole 77.4 g Ca<span> * ( 1 </span>mole Ca<span>/ 40.08 ... n = m / M 1mol </span>Ca<span>weights 40 gmol-1 n = 77,4 / 40 = 1.93 </span>mol<span>.</span>
Answer:

Explanation:
The activation energy represents the energy barrier that reagents must pass to transform into products (or products to transform into reagents in a reverse reaction)
For any reaction, the change in enthalpy is related to the activation energy by the equation

So, the activation energy for the reverse reaction is

Answer:
Answer: a) 20g of H2O (18.02 g/mol) molecules=6.68x10^23
Explanation:
In order to find the amount of molecules of each of the options, we need to follow the following equation.

So, let´s get the number of molecules for each of the options.





the smalest number is in option a)
Best of luck.
1s2 2s2 2p2 i hope this helps