Chapter 9 An overview of chemical reaction Chemical reactions happen in nature to produce natural substance, and even living organism Chemical reactions have been used by us to produce millions of substance that do not exist in nature Chemical reactions are the central part of the chemical sciences
Chapter 9 An overview of chemical reaction Chemical reactions happen in nature to produce natural substance, and even living organism. Chemical reactions have been used by us to produce millions of substance that do not exist in nature. Chemical reactions are the central part of the chemical sciences
9. 1 Chemical reactions are represented by chemical equations During a chemical reaction, one or more new compounds are formed as a result of the rearrangement of atoms The chemical reaction can be represented by a chemica/ equation(化学反应式), Which shows the substances about to react, called reactants(反应物),t the left of an arrow that points to the newly formed substances, called products(产物) reactant s products
9.1 Chemical reactions are represented by chemical equations During a chemical reaction, one or more new compounds are formed as a result of the rearrangement of atoms. The chemical reaction can be represented by a chemical equation (化学反应式), which shows the substances about to react, called reactants (反应物), to the left of an arrow that points to the newly formed substances, called products (产物)
Law of mass conservation(质量守恒定律) matter is neither created nor destroyed during a chemical reaction. The finding of oxygen resulted from this law The chemical equation must be balanced(平衡) Two hydrogen molecules One oxygen molecule Two water molecules 2H2 十 2H,O
Law of mass conservation (质量守 恒定律): matter is neither created nor destroyed during a chemical reaction. The finding of oxygen resulted from this law. The chemical equation must be balanced (平衡)
9.2 Chemists use relative masses to count atoms and molecules How to measure a specific number of atoms and molecules? By relative masses or molar mass(摩尔质量). 2H2 2 HO 2 moles 1 mole 2 moles Which is Which is Which is 4 grams 32 grams 36 grams Which is Which is which is 12.04×1023 molecules 6.02×1023 molecules 12.04×1023 molecules
9.2 Chemists use relative masses to count atoms and molecules How to measure a specific number of atoms and molecules? By relative masses or molar mass (摩尔质量). 2H2 + O2 = H2O 2 moles 1 mole 2 moles Which is Which is which is 4 grams 32 grams 36 grams Which is Which is which is 12.04×1023molecules 6.02×1023molecules 12.04×1023molecules
9.3 Reaction rate(反应速率)is influenced by concentration and temperature How fast is a given reaction? Kinetics(动力学) Reaction rate can be determined by how fast the product generates or the reactant disappears time (a) Low concentration of high concentration of products, high roducts. low o Reactants o Products concentration of concentration of reactants reactants
9.3 Reaction rate (反应速率) is influenced by concentration and temperature How fast is a given reaction? Kinetics (动力学) Reaction rate can be determined by how fast the product generates or the reactant disappears. time Low concentration of products, high concentration of reactants high concentration of products, low concentration of reactants Reactants Products