Chemistry, 26.09.2019 22:20 dramaqueenactr2040

Find the percent by mass of tin in the original sample, assuming that it contains no other reducing agents. a sample of impure tin of mass 0.528 g is dissolved in strong acid to give a solution of sn2+. the solution is then titrated with a 0.0448 m solution of no3−, which is reduced to no(g). the equivalence point is reached upon the addition of 4.03×10−2 l of the no3− solution.

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Answer from: Kjcampbell2

Explanation:

The balanced equation for the given reaction is as follows.

$2NO^{-}_{3}(aq) + 3Sn^{2+}(aq) + 8H^{+} \rightarrow 2NO(g) + 3Sn^{4+} + 4H_{2}O$

Number of moles of $NO^{-}_{3}$ consumed will be calculated as follows.

No. of moles = $Molarity \times {\text{volume in L}}$

= $0.0448 M \times 4.03 \times 10^{-2} L$

= $0.181 \times 10^{-2} mol$

From the balanced equation, we get to know that 2 moles of $NO^{-}_{3}$ reacts with 3 moles of $Sn^{2+}$ .

$0.181 \times 10^{-2}$ moles of $NO^{-}_{3}$ reacts with M moles of $Sn^{2+}$ .

M = $\frac{0.181 \times 10^{-2}mol}{2}$

= $0.09 \times 10^{-2} mol$

It is known that molar mass of tin is 118.71 g/mol. Hence, mass of Sn reacted will be as follows.

m = $0.09 \times 10^{-2}mol \times 118.71 g/mol$

= $10.68 \times 10^{-2} g$

So, percent mass of tin in the original sample = $\frac{\text{mass of tin reacted}}{\text{mass of sample}} \times 100$

= $\frac{10.68 \times 10^{-2} g}{0.528 g} \times 100$

= 20.23 %

Thus, we can conclude that mass of tin is 20.23 %.

Answer from: Quest

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( $n_2$ ) .

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.

Answer from: Quest

when the volume of gas is changed from 717.73 ml to 852 ml the temperature will change from 315 c to 452 c

calculation

this is calculated using the charles law formula

that is, v1/t1 = v2/t2

v1=?

t1 = 315 c into kelvin = 315 +273 = 588 k

v2 = 852 ml

t2 = 425c + 273 =698 k

make v1 the subject of the formula ( by multiplying both side by t1)

v1=( v2 xt1) / t2

v1= (852 ml x 588 k)/ 698 k= 717.73 ml

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