Correctly identify the generic formula for a double replacement reaction.

a. ab + cd + ad + cb
d. cxhy + o2 → co2 + h2o
b. ab + a+b
e. ab + c → ac + b
c. a + b → ab

AB + CD → AC +BD

Explanation:

Double replacement:

It is the reaction in which two compound exchange their ions and form new compounds.

AB + CD → AC +BD

Example:

The following reaction is double replacement reaction.

CaCO₃ + 2HCl  → CaCl₂ + H₂CO₃

While,

A + B → AB

Synthesis reaction:

It is synthesis reaction. The reaction in which two or more simple substance react to give one or more complex product.

AB → A + B

Decomposition:

It is the decomposition reaction. The reaction in which one reactant is break down into two or more product.

AB + C → AC + B

Single replacement:

It is the reaction in which one elements replace the other element in compound.

0.018 moles of isooctane must be burned to produce 100 kJ.

Explanation:

When the isooctane is burned, it undergoes a reaction known as combustion, in which reacts with oxygen to produce carbon dioxide and water. In standard conditions (Pressure = 1 atm and Temperature = 298 K) formed water is liquid. The balanced equation is:

C₈H₁₈(l) + 12.5 O₂(g) ⇄ 8 CO₂(g) +  9 H₂O(l)

The standard enthalpy of combustion (which can be found in tables) relates the amount of isooctane that reacts and the heat the reaction liberates. In this case, ΔH°c = -5,460 kJ/mol, that is every 1 mol of isooctane that burns, 5,460 kJ of heat are released.

We can begin with the information of 100 kJ and apply this conversion factor. Since this energy is released, by convention, we write it with a minus sign.