Essential Question (pg. 141): How do I know if a chemical reaction has occurred and what types of reactions are there? 4 indications of a chemical reaction: Gas formation, solid formation, color change, energy change 7 reaction types: Synthesis, decomposition, single replacement, double replacement, combustion, endothermic reaction, exothermic reaction.

What are 4 ways scientist can tell that a chemical reaction has occurred? 1.Gas formation 2.Solid formation 3.Color change 4.Energy change

What type of reaction occurs when two different elements combine to form one new compound? Synthesis reaction

Your Questions: 1.What is the difference between endothermic and exothermic reaction? Endothermic: energy is absorbed in the reaction. Exothermic: energy is released in the reaction. 2. What are the two products of combustion? Carbon dioxide and water

Essential Question (pg. 157): How do I balance a chemical reaction? Refer to the 5 steps on page 156.

What part of the chemical formula is changed to balance it? The coefficient Why must chemical equations be balanced? According to the law of conservation of mass, the number of atoms of each element in the reaction must equal to the number of atoms of each element in the product.

Your Question: Why can’t you change the subscripts when balancing a chemical reaction? If you change the subscript, then you are changing the compound and its properties.

Essential Question (pg. 143): Why do some chemical reactions get hot and others get cold? Some chemicals get hot because they release energy in the form of heat in a chemical reaction. Others get cold because they absorb energy in the form of heat in a chemical reaction.

Where is chemical energy stored? In the chemical bonds between the atoms If a chemical reaction occurs in a beaker and the beaker feels cold what type of reaction is it? Endothermic reaction

Your Question: What is the difference between endothermic and exothermic reaction? Refer to the two bullet points on page 142. Endothermic reaction: more energy is needed to break the bonds in the reactants than to form new bonds in the product. Therefore, these reactions absorb energy from the environment. Exothermic reaction: more energy is released when bonds form in the product than is used to break bonds in the reactants. Therefore, the extra energy is released to the environment.

Warm up: Write the following chemical equations in word: __Al + __ NiBr 2  __ AlBr 3 + __ Ni __________________________________________________________ __C 2 H 4 + __ O 2  __ CO 2 + __ H 2 O __________________________________________________________