Question

In a popular classroom demonstration, solid sodium is added to liquid water and reacts to produce hydrogen gas and aqueous sodium hydroxide.

Part A Write a balanced chemical equation for this reaction. Express your answer as a chemical equation. Identify all of the phases in your answer.

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Write the balanced chemical equation for each reaction.

Part B - 3.79a Solid lead(II) sulfide reacts with aqueous hydrobromic acid to form solid lead(II) bromide and dihydrogen monosulfide gas. Express your answer as a chemical equation. Identify all of the phases in your answer.

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Balance each of the following chemical equations. Give your answer as coefficients separated by commas.

Part C - 3.84a

Na2S(aq)+Cu(NO3)2(aq)→NaNO3(aq)+CuS(s)

Express your answers as integers separated by commas.

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Part D - 3.84b

N2H4(l)→NH3(g)+N2(g)

Express your answers as integers separated by commas.

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Answer 1

A)

solid sodium = Na(s) ; liquid water = H2O(l) ; produces --> Hydrogen gas = H2(g) and Aqueous sodium hydroxide, NaOH(aq)

Then

Na(s) + H2O(l) ---> NaOH(aq) + H2(g)

balance:

Na(s) + H2O(l) ---> NaOH(aq) + 1/2H2(g)

if integer numbers are required:

2Na(s) + 2H2O(l) ---> 2NaOH(aq) + 2*1/2H2(g)

2Na(s) + 2H2O(l) ---> 2NaOH(aq) + 2*H2(g)

PART B)

Solid lead(II) sulfide reacts with aqueous hydrobromic acid to form solid lead(II) bromide and dihydrogen monosulfide gas.

Solid lead(II) sulfide -- >PbS(s)

aqueous hydrobromic acid --> HBr(aq)

solid lead(II) bromide --> PbBr2(s)

dihydrogen monosulfide gas.--> H2S(g)

PbS(s) + HBr(aq) --> PbBr2(s) + H2S(g)

Balance:

PbS(s) + 2HBr(aq) --> PbBr2(s) + H2S(g)

C)

balance:

Na2S(aq)+Cu(NO3)2(aq)→NaNO3(aq)+CuS(s)

Nalace Na

Na2S(aq)+Cu(NO3)2(aq)→2NaNO3(aq)+CuS(s)

this is now balanced

1,1,2,1

D)N2H4(l)→NH3(g)+N2(g)

balance H via N2H4 and NH3

3N2H4(l)→ 4NH3(g)+N2(g)

N --> 3*2 = 6; 4 + 2 = 6

H--> 3*4 = 12 ; 4*3 = 12

this is now balanced

3N2H4(l)→ 4NH3(g)+N2(g)

3,4,1