chemical reactions yr 8 Flashcards
how can you tell when a new substance has been formed?
permanent colour change
a gas is given off
change in temp
light is produced
why are substances different
the properties are determined by the type of atoms it contains and how those atoms are arranged
what is a chemical reaction
the process of rearranging atoms to form new substances
what are reactants
the old substance (the substance that changes in a chemical reaction)
what are products
the new substances that are formed
what happens when magnesium and oxygen gas are heated
a new substance called Magnesium oxide is the product of the reaction
what is the word equation between hydrogen gas and chloride gas to form hydrogen gas.
hydrogen gas + chlorine gas = hydrogen chloride
why is evaporation a physical change
because the atoms do not rearrange to form different molecules
what is combustion
the term given to any chemical reaction that involves burning with oxygen to release light and heat
when does an explosion occur ?
when so much energy is released so quickly
what are some examples of combustion
the burning of fuels such as petrol, gas, coal, wood and paper
what are some ways that humans have used combustion since prehistoric times
for heat and light
shaping metals
steam engines
electricity generation
what is photosynthesis
a series of chemical reactions that uses sunlight to convert water and carbon dioxide to oxygen gas and glucose
what is the reaction for photosynthesis
carbon dioxide + water = oxygen gas + glucose
where does photosynthesis occur
only in plants as the chemical reaction requires chlorophyll which is only found in plants
