Using 3 O2 molecules and 5 H2 molecules, how many water molecules can be produced? Do you have any left over?

5 molecules of water are formed.

1 Oxygen atom is left over.

Explanation:

Hydrogen reacts with oxygen to form water.

H₂ + O₂ - H₂O

We need to balance the above equation. On balancing we get,

2H₂ + O₂ - 2H₂O

When 3 O₂ molecule reacts with 5H₂O, then the equation becomes

5H₂ + 3O₂ - 5H₂O  + O

5 molecules of water are formed.

1 Oxygen atom is left over.

answer: the enthalpy of the overall chemical reaction is +87.88 kj or +88 kj.

according to hess's law, the overall enthalpy of a reaction is the difference between the sum of enthalpy values of all the products and the sum of enthalpy values of all the reactants.

δh(reaction) = ∑nδh(products) - ∑nδh(reactants)

δh(reaction) = [δh +δh] - [δh]

δh(reaction) = [1(-287.02) + 1(0) ] - [1(-374.9)] kj = +87.88 kj

here, δh (pcl3) = -287.02 kj, δh(cl2) = 0, δh(pcl5) = -374.9 kj

therefore, enthalpy of the overall reaction is +87.88 kj or +88 kj.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.