In general terms, exothermic reactions release energy, so the energy goes from the system to the surroundings.
First you need to work out what mass of 84g of stainless steel is nickel, and because there's 5% you can simply divide by 20, giving 4.2g
For this you can use the equation
The mass, as was worked out previously, is 4.2g
The Mr, which is found on the periodic table, is 28
Moles =
= 0.15mol
1mol = 6.023 x
atoms
So, 0.15mol = 0.15 x 6.023 x
= 9.0345 x
atoms
Given:
n = 0.0021 mol
M = 44 gram/mol
Required: m or the mass of the molecule
Solution:
M = m/n
Rearranging the expression,
m = M x n
m = 44 g/mol x 0.0021 mol
Evaluating the expression and cancelling units, we obtain,
m = 0.0924 grams
M is the molar mass. This value is very useful in chemistry calculations especially in calculating the amounts of reactants and products for a chemical reaction.