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Chemical Reactions
8th Grade Describing and Controlling Chemical Reactions
| Question | Answer |
|---|---|
| What is a chemical equation? | A short easy way to show a chemical equation |
| If a molecule of carbon dioxide is involved in a chemical reaction, how is it represented in the chemical equation for the reaction? | CO2 |
| The substance you have at the beginning of a chemical reaction are called the ... | Reactant |
| The substance you have when a chemical reaction is complete are called the ... | Products |
| What do you read the arrow in a chemical equation as meaning? | Yeild |
| At the end of a chemical reaction, what is the total mass of the reactants compared to the total massof the products? | All of the reactants mass added together gives you the products mass. |
| What is the principle called the conservation of mass? | During a chemical reaction, matter is not created or destroyed. All atoms present at the beginning of the reaction are there in the end. |
| Describe and open system. | An open system is where matter can enter or escape, there for the mass won't be the same. |
| What is an example of a closed system? | A pear is sealed in a container and it decays over time. |
| When is a chemical equation balenced? | A chemical equation is balenced when all atoms are equal. |
| A number placed in front of a chemical formula in a chemical equationos called a ... | Coeffiecent |
| What does a coefficient tell you? | How many atoms of an element there are in a reaction. |
| In what 3 catagories can chemical reactions be classified? | Synthesis, Decomposition, Replacement |
| Which catagory of chemical reactions comes froma term that means "to put things together?" | Synthesis |
| The ... is the minimum amount of energy needed to start a chemical reaction. | Activation energy |
| In a reaction that makes water from hydrogen gas and oxygen gas, where does the activation energy come from? | Have to have a spark or heat |
| A reaction that releases energy is ... | exothermic |
| A reaction that absorbs energy is ... | endothermic |
| Why does an exothermic reaction need activation energy? | It needs it to start the reaction |
| What are five factors that affect the rate of a chemical reaction? | Surface area, tempature, concentration, catalyst, inhabitors |
| Why does surface area of a reactant influence the rate of the reaction? | IF you have a bigger surface area then there will be more particles to react. |
| In what way is temperature related to chemical reaction rates? | The higher the temperture the faster the reaction. The lower the temperature the slower the reaction. |
| The amount of substance in a given volume is called ... | Concentration |
| To increase the rate of a reaction, why would you increase the concentration of the reactants? | You would increase it because there would be more paticles to react. |
| What is a catlyst? | A material that increases the rate of a reaction by lowering the activation energy. |
| A biological catalyst is a ... | enzyme |
| Why must living things rely on thousands of catalyst for chemical reactions necessary for life? | They break down food. |
| What is an inhibitor? | A material used to decrease the rate of a reaction. |
| How do most inhibitors work? | They prevent reactants fcrom comeing together |