chemical change Flashcards
What are physical properties? Examples
Things that you can observe using you five senses or measure directly. Sight, touch, taste, hearing and smelling
What are chemical properties? Examples
Are those that describe how a substance combines with other substances to form new chemicals or how a substance breaks up into two or more different substances. Flammability, reactivity and toxicity
What is a chemical change?
Is when the chemical make up is altered, or when new bonds are formed between atom/molecules or when bonds are broken.
What is a physical change?
A physical change is a changing of state which is reversible.
What is a chemical reaction?
Is a chemical change that in which a new product is produced.
What are reactants?
The substances you begin with
What are products?
The substances that are produced
What evidence shows us that a chemical reaction has occurred?
- precipitate
- odour
- bubbles
- increase or decrease in temp
- light is emitted
- change in colour
What is the only way to be certain a chemical reaction has occurred?
Is to identify one or more new products
What is reaction rate?
A measure how quickly a chemical reaction occurs.
What happens when you add heat to the reaction?
- adds energy
- move more rapidly and collide more frequently
How do you slow down a chemical reaction?
By cooling it down
What is a catalyst?
A chemical that speeds up the chemical reaction but is still present once the reaction has finished.
What are catalysts in living things?
enzymes
How can you alter the reactants?
more reactant
increased surface area
less reactant
increasing the concentration
