An aqueous barium chloride solution was added to a 15.0 ml sample of a sodium sulfate solution according to the reaction below. if 1.83 grams of solid were recovered, what was the molarity of the original sodium sulfate solution?

0.523 M

The reaction between barium chloride and sodium sulfate is given by

BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

We are given,

Volume of  Na₂SO₄ = 15.0 mL

Mass of of solid BaSO₄ = 1.83 g

Required to determine the molarity of Na₂SO₄ solution

we will use the following steps

Mass of BaSO₄ = 1.83 g

To get the number of moles we divide mass by the molar mass

Molar mass of  BaSO₄ = 233.38 g/mol

Number of moles = 1.83 g ÷ 233.38 g/mol

                            = 0.00784 moles

From the balanced equation for every 1 mole of sodium sulfate used 1 mole of BaSO₄ was produced.

Therefore, the mole ratio of Na₂SO₄ : BaSO₄ is 1 : 1

Hence, moles of Na₂SO₄ will also be 0.00784 moles

Volume of sodium sulfate = 15.0 mL or 0.015 L

Number of moles = 0.00784 moles

But, molarity = Moles ÷ Volume

                     = 0.00784 moles ÷ 0.015 L

                     = 0.5227 M

                    = 0.523 M

Thus, the molarity of original sodium sulfate is 0.523 M

answer: - 3.) the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

solution: - as per the rules, oxidation number of oxygen in its compounds is -2. the sum of oxidation numbers of all the elements of a molecule or compound is zero.

also, the oxidation number in elemental form is zero.

in no, the oxidation number of o is -2 so the oxidation number of n is +2 so that the sum is zero.

similarly, the oxidation number of c in co is +2 and o is -2.

on product side the oxidation number of n is 0 as it is in the elemental form() .

oxidation number of c in carbon dioxide is +4 as there are two oxygen in it and we know that each oxygen is -2.

so, oxidation number of n is changing from +2 to 0 and the oxidation number of c is changing from +2 to +4.

since nitrogen is reduced and hence no is acting as an oxidizing agent. carbon is oxidized and so co is acting as a reducing agent.

so, the right choice is number 3.)the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.