POSTLABORATORY QUESTIONS 1 Endothermic reactions Reactants

POST-LABORATORY QUESTIONS 1. Endothermic reactions: Reactants + 2. Exothermic reactions: products Reactants products + 3. Sketch the diagram of an endothermic reactions (refer to pre-lab question #6) 4. During chemical reactions the bonds between atoms break and new bonds form. Energy must be absorbed to break a bond, so breaking bonds is endothermic. Making new bonds is exothermic because energy is released. If the reaction equation is: 2H2 (one bond) + 02 (two bonds) 2HsO (two bonds) Is this reaction exothermic or endothermic? Use ideas about bonds to explain why.

Solution

1. Endothermic reaction is the reaction which absorbs heat.

so, Reactants + heat ---> Product

2. Exothermic reactions releases heat into the surroundings.

Reactants = Product + Heat