The scientist should make a new hypothesis and do a new experiment! That is what I say!
The mass of Fe(NO3)2 you have is 245 g * 0.805 = 197.23 g
<span>The molar mass of Fe(NO3)2 is 179.85 g/mole so you have 1.0966 moles </span>
<span>From the balanced equation, that is the number of moles of Fe you make since both Fe(NO3)2 and Fe have a 3 in front of them. </span>
<span>The mass of Fe is 1.0966 moles * 55.85 g/mole (atomic mass of iron) = 61.246 g. From the information you are given, your answer should be in 3 sig figs so 61.2 g </span>
<span>Moles of HCl = 8.2 L * 3.5 mole/L = 28.7 moles </span>
<span>From the balanced equation, you need 1/2 the moles of zinc as you have of HCl so you need 14.35 moles. </span>
<span>To get the mass of zinc, multiply moles of zinc by its atomic mass = 938.2 g. From the information given, your answer should be in 2 sig figs so I would report it as 9.4 * 10^2 g, that clearly shows 2 sig figs.</span>
For a solution to be tested in this experiment and must be buffered to pH of 10, the [OH-] change will be, The hydroxide concentration would be higher and the formation of insoluble hydroxide salts with Mg^2 and Ca^2 would cause the determined concentration of water hardness to be too low.
<h3>What would be the [OH-] change?</h3>
Generally, the equation for the Total hardness is mathematically given as

Where

D=0.02/0.01=2
Therefore

T=1632ppm
in conclusion, The hydroxide concentration would be higher .
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