Answer:
Melting point
Explanation:
Pure substances have sharp melting and boiling points while impurities lower the melting point and raise the boiling point
Solute - the substance that dissolves into the solvent to produce a homogenous mixture
Solvent - the substance in which a solute dissolves to produce a homogeneous mixture
I have done this question before and even though you didn’t provide the options. I think the correct option is elements
Buffer solution resist the change in pH upon addition of small amount of strong acid or strong base.
Buffer consists of weak acid as HF / and its conjugate base NaF
When strong acid as HCl is added to buffer, it respond with its conjugate base to convert the strong acid to weak acid like this:
HCl (S.A) + NaF → NaCl + HF (W.A)
moles of HF we already have = M * V(in liters)
= 0.0955 M * 0.033 L = 3.15 x 10⁻³ mole
moles of HCl added = 8.00 x 10⁻⁵ mole
one mole HCl reacts with 1 mole NaF to give 1 mole HF
so the amount added to HF = 8.00 x 10⁻⁵
Total moles of HF present = (3.15 x 10⁻³) + (8.00 x 10⁻⁵) = 3.23 x 10⁻³ mole
PH = -log[H3O+]
Solving for [H3O+] gives
[H3O+] = 10^-pH
= 10^-3
or 1x10^-3 M
