Mole ratio:
MgCl₂ + 2 KOH = Mg(OH)₂ + 2 KCl
2 moles KOH ---------------- 1 mole Mg(OH)₂
moles KOH ------------------- 4 moles Mg(OH₂)
moles KOH = 4 x 2 / 1
= 8 moles of KOH
molar mass KOH = 56 g/mol
mass of KOH = n x mm
mass of KOH = 8 x 56
= 448 g of KOH
hope this helps!
Answer:
b. 336 kJ
Explanation:
The molar mass of iron is 55.8 g/mol, so the number of moles for 45.4g is:
n = mass/molar mass
n = 45.4/55.8
n = 0.8136 mol
For the reaction given, 4 moles of iron will release 1.65x10³ kJ, so:
4 moles ---------------- 1.65x10³ kJ
0.8136 mol------------ x
By a simple direct three rule:
4x = 1.34x10³
x = 336 kJ
3.47 x atoms of gold have mass of 113.44 grams.
Explanation:
Data given:
number of atoms of gold = 3.47 x
mass of the gold in given number of atoms = ?
atomic mass of gold =196.96 grams/mole
Avagadro's number = 6.022 X
from the relation,
1 mole of element contains 6.022 x atoms.
so no of moles of gold given =
0.57 moles of gold.
from the relation:
number of moles =
rearranging the equation,
mass = number of moles x atomic mass
mass = 0.57 x 196.96
mass = 113.44 grams
thus, 3.47 x atoms of gold have mass of 113.44 grams
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