## Reação de Oxirredução e Massa

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watashiwarans
Newbie
Posts: 1
Joined: Tue Dec 08, 2020 9:11 am

### Reação de Oxirredução e Massa

10) Uma amostra de uma liga que contém cromo, de massa 3,450 g, foi
dissolvida em ácido, e todo o cromo na amostra foi oxidado para CrO4-2
.
Verificou-se, então, serem necessários 3.18 g de Na2SO3 para reduzir o CrO4-2
para CrO2-2
, em uma solução básica, sendo o SO3-2 oxidado convertido a SO4-2
,
em uma solução alcalina.
a) Escreva a equação balanceada para a reação do CrO4-2 com o SO3-2
, em
solução alcalina;
b) Quantos gramas de cromo existiam na amostra?
c) Qual é a porcentagem de cromo na liga?
ChenBeier
Distinguished Member
Posts: 493
Joined: Wed Sep 27, 2017 7:25 am
Location: Berlin, Germany

### Re: Reação de Oxirredução e Massa

10) A sample of an alloy containing chromium, with a mass of 3,450 g, was
dissolved in acid, and all the chromium in the sample was oxidized to CrO4-2
.
It was then found that 3.18 g of Na2SO3 were needed to reduce CrO4-2
for CrO2-2
, in a basic solution, with oxidized SO3-2 converted to SO4-2
,
in an alkaline solution.
a) Write the balanced equation for the reaction of CrO4-2 with SO3-2
, in
alkaline solution;
b) How many grams of chromium were there in the sample?
c) What is the percentage of chromium in the alloy?

1. Develop the redox reaction Chromate/ Chromite and Sulfite/Sulfate
Using alkaline condition means (O) + H2O + 2 e- => 2 OH- Reduction
Oxidation is Visa versa
2. If the equation is known read to many mole Sulfite corespond with chromate.
3. Calculate with actial mass
4. Then calculate mass of chromium and the percentage