. Flashcards
(18 cards)
how is energy moved to surroundings?
energy is transfered to surroundings via light, sound or heat (thermal energy)
what is a hydrocarbon made out of?
a hydrocarbon is made out of ONLY carbon and hydrogen.
what is the word equation for hydrocarbon combustion?
hydrocarbon + oxygen –> water + carbon dioxide
why is combustion also an oxidation reaction?
because the substances react with oxygen.
can metals be oxidised?
yes, metal + oxygen–> metal oxide
what happenes to the mass of the reactants in a reaction?
In a reaction, the mass of the reactants is always the same as the mass of the products.
why do metals appear to gain mass when heated in air?
the difference in mass is the mass of oxygen that reacted.
why do hydrocarbons appear to lose mass in combustion?
the products of the hydrocarbon (carbon dioxide and water vapour) are lost in the air.
what is phlogiston?
Before oxygen was discovered, scientists explained combustion by saying that, as a substance burnt, it gave out a substance called phlogiston to the air.
why was the phlogiston theory not ideal?
becaause scientist could not explain why metals gained mass when they reacted with air
what is a complete combustion?
when the fuel reacts completly with oxygen
what is an incomplete combustion?
when the fuel only partly reacts with oxygen
what are many of the products fro burning fossil fuels?
pollutants, they may harm the habitat or its organisms
what is acid rain?
Acid rain is rain water that is made more acidic by dissolved sulfur dioxide and nitrogen oxides.
what does a catalytic converter do?
removes carbon monoxide
what is the greenhouse effect?
The greenhouse effect is a natural process that warms the Earth’s surface. When the Sun’s energy reaches the Earth’s atmosphere, some of it is reflected back to space and the rest is absorbed and re-radiated by greenhouse gases
What were key things about John Daltons atomic model?
-All matter is made up of tiny particles called atoms.
-Atoms are indestructible, and cannot be created, or destroyed.
-In compounds, each atom of an element is always joined to a fixed
number of atoms of the other elements.
-During chemical reactions, atoms rearrange, to make new substances.
What happenes to the atoms in a chemical reaction (mass)?
The atoms rearanged so, no atoms are lost or gained so the mass of the reactants is equal to the
mass of the products.
