The rate constant for 1st order reaction is
K = (2.303 /t) log (A0 /A)
Where, k is rate constant
t is time in sec
A0 is initial concentration
(6.82 * 10-3) * 240 = log (0.02 /A)
1.63 = log (0.02 /A)
-1.69 – log A = 1.63
Log A = - 0.069
A = 0.82
Hence, 0.82 mol of A remain after 4 minutes.
Answer:
0.29 moles of PbCl₂
Explanation:
Given data:
Mass of lithium chloride = 24.3 g
Moles of PbCl₂ = ?
Solution:
Chemical equation;
PbSO₄ + 2LiCl → PbCl₂ + Li₂SO₄
Number of moles of LiCl:
Number of moles = mass/ molar mass
Number of moles = 24.3 g/ 42.394 g/mol
Number of moles = 0.57 mol
Now we will compare the moles of PbCl₂ with LiCl .
LiCl : PbCl₂
2 : 1
0.57 : 1/2×0.57 = 0.29 mol
Answer:The 1st and 2nd reactions are the example of oxidation -reduction.
Explanation:
Oxidation is basically when a species loses electrons and reduction is basically when the species gains electrons.
A reaction is known as an oxidation -reduction reaction only if oxidation and reduction simultaneously occur in the reaction. It basically means if a species is getting oxidized in the reaction then the other species present in the system must be reduced in the reaction.
Oxidation-reduction reactions are also known as redox reactions.
In the 1st reaction the oxidation state of Na in reactant is 0 and in products is +1 hence Na is oxidized and the oxidation state of chlorine is 0 in reactants and in products is -1 so chlorine is reduced. Hence Na is oxidized and Cl is reduced so the reaction is a example of oxidation-reduction.
2Na(s)+Cl₂(g)→2NaCl(s)
In the second reaction the oxidation state of Na in reactant is 0 and in products is +1 hence Na is oxidized and the oxidation state of Cu is +1 in reactant and 0 in products so Cu is reduced. Hence Na is oxidized and Cu is reduced so the reaction is an example of oxidation-reduction.
Na(s)+CuCl(aq)→NaCl(aq)+Cu(s)
In the third reaction the oxidation state of Na changes from +1 to +1 and that of Cu also changes from +1 to +1. So there is no change in oxidation state of the species present in reactants and products. Hence this reaction is not an example of oxidation and reduction.
at 70°C = 130 gram
NaCl at 100°C= 40 gram
NH₂Cl at 90°C= 70 gram
<h3>What is solubility?</h3>
Solubility is defined as the maximum amount of a substance that will dissolve in a given amount of solvent at a specified temperature.
Amount of a substance (called the solute) that dissolves in a unit volume of a liquid substance (called the solvent) to form a saturated solution under specified conditions of temperature and pressure. Solubility is expressed usually as moles of solute per 100 grams of solvent.
Hence,
at 70°C = 130 gram
NaCl at 100°C= 40 gram
NH₂Cl at 90°C= 70 gram
Learn more about solubility here:
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