I believe the answer is: in order not to write very big or very small number values
This is an acid-base reaction where HF is the acid and H2O is the base (it's amphoteric and can be an acid or a base). The products would then H3O+ (the conjugate acid) and F- (the conjugate base). Now, we can simply construct a reaction using the found products and reactants. This acid-base reaction would be HF + H2O <--> H3O+ + F-.
Hope this helps!
Answer:
number of moles = 0.21120811
Explanation:
To find the number of moles, given the mass of the solute, we use the formula:




Label the variables with the numbers in the problem:



The first thing we have to do is find the molar mass of sodium sulfate, in order for us to use the formula for finding the number of moles:
Formula for finding the molar mass of sodium sulfate:

For the variables and what they mean are below for finding the molar mass of sodium sulfate:





Plug the numbers into the formula, to find the molar mass of sodium sulfate:











Now that we have found the molar mass, we can calculate the number of moles in the solution of sodium sulfate with the formula:








0.21120811 rounded gives you 0.2112
or if you did the problem without decimals
30 grams of sodium sulfate divided by its molecular weight – which we found to be 142 – gives us a value of 0.2113 moles.