CHEMISTRY QUESTIOn?

Question

Write a balanced equation for the decomposition of baking soda (NaHCO3). One of the products is Na2CO3.

Then, calculate that mass of NaHCO3 required to produce 20.5g of CO2.

I need help terribly on this problem. PLease help me

Answer 1

The balanced chemical equation for the decomposition of baking soda is the following:

2 NaHCO3 => CO2 + Na2CO3 + H2O

Calculating the mass of NaHCO3 required to produce 20.5 g of carbon dioxide is a stoichiometry (mass to mass) conversion.

Step #1 convert given mass of CO2 to moles of CO2

You need the molar mass of CO2 to complete this step.

Molar masses for elements are equal to their atomic weight (found on a periodic table)
Molar mass of carbon: 12.0 g/mole
Molar mass of oxygen: 16.0 g/mole

In CO2, there is 1 atom of carbon and 2 atoms of oxygen.

Therefore (12.0+16.0+16.0)= 44.0

The molar mass of CO2 is 44.0 g/mole.

Then,
20.5 g CO2 divided by 44.0 g/mole CO2 = 0.466 mole CO2

Step 2: convert moles of CO2 to moles of NaHCO3

You complete this step using what is called the “mole ratio.” The mole ratio in a balanced chemical equation is equal to the coefficients of the substances in the problem.

In this problem, you are interested in converting between CO2 and NaHCO3.

So, the mole ratio you are interested in using is…

2 moles NaHCO3 = 1 mole of CO2
Note the “2” and the “1” are the respective coefficients of the substances in the balanced equation. Remember that if there is no coefficient in the balanced equation, a ‘1” is assumed.

Answer from step 1: 0.466 moles of CO2

Take moles of CO2 and multiply it by the mole ratio as a fraction. Remember to place the unit you want to eliminate in the denominator (in this case CO2 goes on the bottom)

0.466 mole CO2 x (2 mole NaHCO3 / 1 mole CO2) = 0.932 mole NaHCO3

Step 3: convert moles of NaHCO3 to grams of NaHCO3

To complete this step, you need the molar mass of NaHCO3.

This calculation is similar to the molar mass calculation you completed in step 1.

Molar mass of sodium = 23.0 grams per mole (one atom in compound)
Molar mass of hydrogen = 1.0 grams per mole (one atom in compound)
Molar mass of carbon = 12.0 grams per mole (one atom in compound)
Molar mass of oxygen = 16.0 grams per mole (three atom in compound)

Molar mass of NaHCO3 = (23.0+1.0+12.0+16.0+16.0+16.0) = 84 grams per mole NaHCO3

Answer from part 2: 0.932 moles NaHCO3

You now use the molar mass to convert from moles to mass.

0.932 moles NaHCO3 x 84 grams/mole NaHCO3 = 78.3 grams NaHCO3

I hope this answer helps you. I thought I would go through step by step rather than just solve and give you the answer.

Answer 2

Not so difficult, is it?

2 Na2HCO3 -> H2O + CO2 + Na2CO3

the molecular weight of CO2 = 44

20.5 g CO2 = 20.5/44 mol CO2

so you need 2*20.5/44 mol Na2HCO3 to produce the necessary amount of CO2

MW of NaHCO3 = 23+1+12+48=74

soooo

74*2*20.5/44 g of NaHCO3 is required to get 20.5 g of CO2

Answer 3

2NaHCO3-->H2O+Na2CO3- this is the reaction

Ar(C)=12
Ar(H)=1 ......................... Ar= atomic relative mass
Ar(O)=16 ..........................Mr= molecular relative mass
Ar(Na)=23

Mr(NaHCO3)=84 ( but there are two molecules so it will be 84*2=168)
Mr(CO2)=56

Then you make a proportion:

With 168 gr. of NaHCO3 you get 56 gr. CO2
With x gr. of NaHCO3 you get 20.5 gr. of CO2 ..................x= gr. of NaHCO3
-----------------------------------------------------------
So:
168*20.5=56*x
x=(168*20.5)/56
x=61,5 gr. of NaHCO3- this is the result, the one up isn't correct trust me