No change mass of copper cube will be the same
Answer:
Henderson Hasselbalch equation: pH = pKa + log [salt]/[acid]
You need to know the pKa for acetic acid. Looking it up one finds it to be 4.76
(a). pH = 4.76 + log [0.13]/[0.10]
= 4.76 + 0.11
= 4.87
(b) KOH + CH3COOH =>H2O + CH3COOK so (acid)goes down and (salt)goes up. Assuming no change in volume, you have 0.10 mol acid - 0.02 mol = 0.08 mol acid and 0.13 mol salt + 0.02 mol = 0.15 mol salt
pH = 4.76 + log [0.15]/[0.08]
= 4.76 + 0.27
= 5.03
The empirical formula is Fe₃O₄.
The empirical formula is the <em>simplest whole-number ratio of atoms</em> in a compound.
The ratio of atoms is the same as the ratio of moles, so our job is to calculate the molar ratio of Fe to O.
I like to summarize the calculations in a table.
<u>Element</u> <u>Moles</u> <u>Ratio</u>¹ <u>×3</u>² <u>Integers</u>³
Fe 0.77 1 3 3
O 1.0 1.3 3.9 4
¹ To get the molar ratio, you divide each number of moles by the smallest number (0.77).
² If the ratio is not close to an integer, multiply by a number (in this case, 3) to get numbers that are close to integers.
³ Round off these numbers to integers (3 and 4).
The empirical formula is Fe₃O₄.
