Wednesday
August 27, 2014

Homework Help: chem

Posted by Jenn on Tuesday, February 20, 2007 at 2:04pm.

which of the following is a chemical reaction?

A) propane forms a flame and emits heat as it burns.

B) Acetone feels cold as it evaporates from the skin.

C) Bubbling is observed when potassium carbonate and hydrochloric acid solutions are mixed.

D) Heat is felt when a warm object is placed in your hand.

I think that A and C are chemical reactions. Is that correct?


I have to write out these following equations with correct chemical symbols and such.
Can you check my work? I know it looks horrible!

A) Solid lead(II) reacts with aqueous hydrochloric acid to form solid lead(II) chloride and dihydrogen sulfide gas.

My answer: PbS(s) + HCl(aq) --> PBCl + H(subscript2)S

B) Gaseous carbon monoxide reacts with hydrogen gas to form gaseous methane and liquid water

My answer: CO(g) + H(g) ---> CH(subscript4)(g) + H(subscript2)O

C) Solid iron(III) oxide reacts with hydrogen gas to form solid iron and liquid water

My answer: Fe(subscript3)O(s) + H(g) ---> Fe+H(subscript2) O

D) Gaseous ammonia reacts with gaseous oxygen to form gaseous nitrogen monoxide and gaseous water

My answer: NH(subscript3)(g) + O(g) ---> NO(g) + H(subscript2) O(g)


which of the following is a chemical reaction?

A) propane forms a flame and emits heat as it burns.

B) Acetone feels cold as it evaporates from the skin.

C) Bubbling is observed when potassium carbonate and hydrochloric acid solutions are mixed.

D) Heat is felt when a warm object is placed in your hand.

I think that A and C are chemical reactions. Is that correct?

That is correct. B and D are physical changes.

I have to write out these following equations with correct chemical symbols and such.
Can you check my work? I know it looks horrible!

A) Solid lead(II) reacts with aqueous hydrochloric acid to form solid lead(II) chloride and dihydrogen sulfide gas.

My answer: PbS(s) + HCl(aq) --> PBCl + H(subscript2)S
Why did you start this way. The problem states lead (II). Why did you start with PbS and not Pb? Actually, the problem is flawed because there is a Pb(II) ion but there is no such thing as SOLID Pb(II). The prof may have intended this as a hint that the valence of Pb is +2 in this reaction since Pb has two common valences; i.e., +2 and +4.

B) Gaseous carbon monoxide reacts with hydrogen gas to form gaseous methane and liquid water

My answer: CO(g) + H(g) ---> CH(subscript4)(g) + H(subscript2)O

H comes as a diatomic molecules when it is not combined with another atom. And your equation isn't balanced either. Here is the way it will look.
CO(g) + 3H2(g) ==> CH4(g) + H2O(l)

C) Solid iron(III) oxide reacts with hydrogen gas to form solid iron and liquid water

My answer: Fe(subscript3)O(s) + H(g) ---> Fe+H(subscript2) O

iron(III) oxide is Fe2O3. Do you not know how to write the formulas when you know the valence (oxidation state)? H should be diatomic. Fe on the right should show (s) and H2O should be H2O(l). I will let you redo it.

D) Gaseous ammonia reacts with gaseous oxygen to form gaseous nitrogen monoxide and gaseous water

My answer: NH(subscript3)(g) + O(g) ---> NO(g) + H(subscript2) O(g)

O comes as a diatomic molecule when it isn't combined with another atom. There is a fairly simple way of know which atoms are diatomic. That means it must be rebalanced although it isn't balanced now, either.

For Further Reading



I should have said that I wanted to solve the balances afterward.
I wanted someone to check if the lettering was correct.

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