Chemistry Flashcards
Endothermic reaction
A reaction where the energy is greater in the products than in the reactants
Exothermic Reaction
A reaction where energy is greater in the reactants than the products
Combustion
When an element, compound, or hydrocarbon is burnt in oxygen to produce significant heat and light
Neutralisation
A reaction where an acid is neutralised by a base and vice versa to form a salt and water
Acid
A compound that release hydrogen ions
Bases
A compound producing hydroxide ions
Qualities of acids
pH less than 7, they can be highly corrosive
Qualities of bases
pH greater than 7, solution referred to as an alkaline
Name some very strong and weak acids
Strong: sulphuric acid, hydrochloric acid, nitric acid
Weak: acetic acid, ethanoic acid, lactic acid, citric acid
What are caustic bases and what is an example?
Caustic bases are corrosive bases and an example is sodium hydroxide
Where do we use mild forms of bases?
Cleaning products, soap, toothpaste
What is the pH level of water and what is it defined as?
The pH level is 7 and it is neutral.
Precipitation
When two clear solutions mix to form a soluble product and an insoluble solid, labelled as the precipitate
Acid - metal
When an acid reacts with a metal to produce a salt and hydrogen gas
Name some very reactive metals
Sodium, potassium, calcium
Acid - carbonate
When an acid reacts with a carbonate to produce water, carbon dioxide and a salt
What are acid-carbonate reactions used for?
Cleaning up spills
Respiration
Chemical reaction in all living cells. It involves the combination of glucose with oxygen to produce carbon dioxide and water. The reaction produces energy so the organism can live, move and grow. It is a slow process.
Corrosion
Metals combining with oxygen gas will form metal oxides. This includes the rusting of iron and steel.
Difference between corrosion and combustion
Corrosion occurs more slowly in comparison with combustion and doesn’t produce significant amounts of heat and light.
What is the rate of reaction?
The speed at which a chemical reaction occurs?
How can temperature control the rate of reaction?
Increasing the temperature increases the speed of the particles in liquids and gases so the particles will collide more frequently. The particles also get more energy so when they collide, they hit harder so chemical bonds are likely to break the atoms so they can form their products.
How can the concentration control the rate of reaction?
Particles are more likely to collide if concentration is increased and react more often.
How can agitation control the rate of reaction?
It ensures reactants are kept in contact by removing the build-up of products around reactants
How can surface area control the rate of reaction?
If crushed into small pieces (preferably a powder), more of the reactants are exposed to other reactants so they all react at the same time, hence the reaction is faster
How can catalysts control the rate of reaction?
They speed up chemical reactions naturally but are not consumed in the reaction. They reduce the amount of energy required in converting reactants into products and the make it easier for reactants to combine and form molecules.
