Question

A. Classify each of the following reactions as decomposition, combination, combustion,

1. 2CH3OH(l)+3O2(g)→2CO2(g)+4H2O(g)
2. 2KClO3(s)→2KCl(s)+3O2(g)
3. S(s)+3F2(g)→SF6(g)
4. CaO(s)+H2O(l)→Ca(OH)2(aq)
5. 2Cu(NO3)2(s)→2CuO(s)+4NO2(g)+O2(g)

B. Solid aluminum metal and diatomic chlorine gas react spontaneously to form a solid product. Give the balanced chemical equation (including phases) that describes this reaction.

Indicate the phases using abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively.

Express your answer as a chemical equation.

C. When heated, solid copper(II) carbonate decomposes to solid copper(II) oxide and carbon dioxide gas. Give the balanced chemical equation (including phases) that describes this reaction.

Indicate the phases using abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively.

Express your answer as a chemical equation.

D. A flask contains 0.470 mol of liquid bromine, Br2. Determine the number of bromine molecules present in the flask.

Express your answer numerically in molecules.

E. A compound is 40.0% C, 6.70% H, and 53.3% O by mass. Assume that we have a 100.-g sample of this compound.

The molecular formula mass of this compound is 210 amu . What are the subscripts in the actual molecular formula?

Enter the subscripts for C, H, and O, respectively, separated by commas (e.g., 5,6,7).

F. An unknown compound contains only carbon, hydrogen, and oxygen (CxHyOz). Combustion of 3.00 g of this compound produced 4.40 g of carbon dioxide and 1.80 g of water. How many moles of hydrogen, H, were in the original sample?

Express your answer to three significant figures and include the appropriate units.

G. How many grams of NH3 can be produced from 2.82 mol of N2 and excess H2.

Express your answer numerically in grams.

H. How many molecules (not moles) of NH3 are produced from 7.51×10⁻⁴ g of H2?

Express your answer numerically as the number of molecules.

I. 2C8H18(g)+25O2(g)→16CO2(g)+18H2O(g)

1. How many moles of water are produced in this reaction?

Express your answer with the appropriate units.

2. After the reaction, how much octane is left?

Express your answer with the appropriate units.

Answer 1

Answer:-

A. As we know that decomposition reaction is that reaction in which one complex molecule or salt break down into simpler molecules. e.g. decomposition of CaCO_3(s)

CaCO_3(s)   CaO_(s) +  CO_2(g)

- Combination reactions are generally known as Direct combination reaction in which two or more reactants reacts together to form one single product. e.g. formation of HI

H_2(g) +  I_2(g)   2HI_(g)

- Combustion reaction is that reaction in which molecule reacts with excess of Oxygen to form carbon dioxide and water. e.g. combustion of ethane (C₂H₆)

2C₂H_6(g) + 7O_2(g)​​​​​​​   4CO_2(g) + 6H₂O_(g)

(I)-

2CH₃OH_(l) + 3O_2(g) ​​​​​​​   2CO_2(g) + 4H₂O_(g) (Combustion reaction)

(II)-

2KClO_3(s)   2KCl_(s) +  3O_2(g) (Decomposition reaction)

(III)-

_S(s) + 3F_2(g)​​​​​​​   SF_6(g) (Combination reaction)

(IV)-

CaO_(s) + H₂O_(g)​​​​​​​   Ca(OH)_2(aq) (Combination reaction)

(V)-

2Cu(NO₃)_2(s)   2CuO_(s) + 4NO_{2(g)​​​​​​​} + O_2(g)    (Decomposition reaction)

​​​​​​​

B. when solid aluminum metal and diatomic chlorine gas react spontaneously to form a solid AlCl₃. This reaction is an example of combination reaction.

2Al_(s) + 3Cl_2(g)​​​​​​​   2AlCl_3(s) (Combination reaction)

C. When heated, solid copper(II) carbonate decomposes to solid copper(II) oxide and carbon dioxide gas which is given below:-

CuCO_3(s)   CuO_(s) +  CO_2(g) (Decomposition reaction)

D. Given:-

No. of moles of Br₂ =  0.470 mol

No. of molecules of Br₂ = ?

As we know that mole is the unit of chemical substance i.e 1 mole of any substance containing elementary particles like atoms, molecules or ions equal to the Avogadro's number (6.023 10²³). therefore

1 mole of Br₂ contains = 6.023 10²³ Br₂ molecules.

So

0.470 mol of Br₂ contains = 0.470 6.023 10²³ Br₂ molecules.

0.470 mol of Br₂ contains = 2.831 10²³ Br₂ molecules ( i.e the answer)

Note:- I have solved first four questions as per Chegg QA guidelines.