A chemical calculation problem, how to calculate, urgent, question 28, sub question 3, how much meth

Methane fuel cells.

Positive: 2O2 + 8E- +4H2O = 8OH - (at B) Negative: CH4 - 8E- +10OH- = CO32- +7H2O (at A).

Total reaction: CH4 + 2O2 + 2OH = CO32- + 3H2O Since the total reaction consumes OH-, the pH of the solution becomes smaller.

In the electrolytic cell, the iron rod is plated with copper, the iron rod is used as the cathode, and the copper rod is used as the anode.

Anode: Cu-2E- = Cu2+

Cathode: Cu + 2E- = Cu

The concentration of Cu2+ in the solution is unchanged.

The cathode weight gain, indicating that there is a get, then CH4 is required, and the volume is.

It is copper, then it means that the copper is generated, the transferred electrons are, the charge transfer is also conserved, and the copper loses so many electrons, then it means the electrons obtained by CH4. The electrons that can be obtained in CH4 are C to form CO2, and 1molCH4 to generate CO2, where the number of electrons transferred by C is 8mol. So the question of the transferred electrons, means that the reaction of ch4 is.

Convert to volume that is.

Gram of methane = = methane.

Contains carbon god shed to take yuan and zai.

CO2 is generated

co2＝＝

Start by listing the chemical equations for the two reactions that take place:

2na2o2+2h2o=4naoh+o2

2Na2O2+2CO2=2Na2CO3+O2 It can be found that the ratio of H2O and CO2 participating in the reaction to the amount of O2 released is 2:1, and then after analysis, it can be seen that the amount of solid increase is the mass of H2O and CO2, and the amount of decrease is the mass of O2, so the mass of O2 produced is.

So the following relation is obtained:

2(co2+h2o)~~o2

According to the definition of the average relative molecular mass, the average relative molecular mass of the mixture is to hope that it can help you.

.2CO2+2Na2O2*****====Na2CO3+O2 weight gain 88

2H2O+2NaOH**********===4NaOH+O2 weight gain 36

56x/88+4*(

x=y=n(co2)=

n(h2o)=

Mean relative molecular mass of the gas mixture =

First, 2CO2+2Na2O2===2Na2CO3+O22H2O+2Na2O2===4NaOH+O2Then, let the CO2 in the mixed gas have X

g, water vapor has y

g, then x+y=

x/44)/2+(y/18)/2=（

x 44) 2 and (y 18) 2

They are the amount of O2 produced by the two reactions.

Solve the system of equations.

x=y= It can be calculated that the amount of CO2 and O2 in the mixed gas is the total amount of the mixed gas, respectively.

Therefore, the average relative molecular mass of the gas mixture is.

g/mol

2fe(oh)3=fe2o3+3h2o

Red Fe2O3 powder.

Calculate the fe for.

It turned out to be added.

Then there is Fe in the original compound

Fe2+ is completely precipitated.

2Fe2+ +4OH- +O2=2Fe(OH)3 is calculated to have Fe

Then "only a pure oxynate (non-double salt) without crystalline water can be obtained, and there is no Fe2+ in the original solution, then the salt is K2SO4

Or the consumption is calculated by Fe2+ just completely precipitated.

So there's potassium from compounds.

Suppose x:fe:k=1:2:4 The quality of the calculation does not match the problem.

fe:k=1:2 then x=fe y=k

It can be calculated that the molar mass of the compound is 198

198-56-78) 4=16g mol z=o The compound is K2FeO4

If the mass of nitrogen is equal, the number of nitrogen-containing atoms is also equal.

nh4no3---co(nh2)2

80 60x 100kg80/x=60/100kgx=

If the mass of nitrogen is equal, the number of nitrogen-containing atoms is also equal.

80/x=60/100kgx=

It is to write the equation first, and then mark the known molecular mass, and then you can set what you are looking for as x to solve the equation.