Ch. 2 Chemisty of Life 2.4 Chemical Reactions

Monday August 30 Warm-up 1.Draw a water molecule showing hydrogen bonds 2.List 3 properties of water 3.Lemon juice has pH=2—is it acidic or basic? 4.What is the difference in H+ ion concentration b/w lemon juice (pH=2) and tomato juice (pH=4)

1.

2. Lemon Juice is acidic 3. Lemon juice has a H+ concentration 100 times greater than Tomato juice.

Bonds break during chemical reactions. Chemical Reactions: process that changes substances into different substances by breaking and forming chemical bonds. EX: carbon dioxide and water vapor you breathe out is made by chemical reactions

Reactants, Products, & Bond Energy

Bond Energy: the amount of energy that will break a bond between two atoms. The same amount of energy is needed to break apart a bond as was used to form the bond.

Chemical Equilibrium Equilibrium = Balance Many reactions move in both directions depending on the concentrations of the reactants/products CO2 + H2O H2CO3 Equilibrium: when both the reactants and products are made at the same rate.

Energy & Chemical Reactions Activation Energy-the amount of energy that needs to be absorbed for a chemical reaction to start. Ex: pushing a rock up hill (see fig. 2.20)

Endothermic Reaction Absorbs more energy than it releases Total energy released

Releases more energy than it absorbs

Differenc between both… Endothermic 1. Chemical reaction absorbing more energy than it releases. 2. Bond energy is higher in product Ex: Photosynthesis Exothermic 1. Chemical reaction releasing more energy than it absorbs (the excess is often given off as heat or light) 2. Bond energy is lower in product Ex. Cellular Respiration Fireflies, Angler Fish, Squid

2.5 Enzymes What does adding energy to a reaction do?

Catalyst- Decreases activation energy Needed and increases reaction rate. Ex: the rock being pushed up hill A catalyst could be a dolly.

Enzymes- Catalysts for chemical reactions in living things Enzymes are proteins Enzymes are involved in almost every process in organisms Temperature and pH can affect shape, function, & activity of enzyme Ex: Amylase is enzyme in saliva that breaks down starch into simple sugars

Substrate- the reactants that an enzyme acts on. Ex. Amylase is enzyme that breaks down starch. - starch is the substrate Substrates fit perfectly (like a key) into the active site of enzymes. Enzyme Structure allows only certain reactants to bind

LOCK and KEY MODEL

This is why if an enzyme’s structure Changes, it may not work at all.