Chemical Reactions
Identify the 5 states of matter we use in chemical reactions.
Solid (s), Liquid (l), Gas (g), Aqueous (aq), Precipitate (ppt).
Which of the follow demonstrates the Law of Conservation of Mass?
a) 3g of magnesium reacts with 2g of chlorine gas to produce 6g of magnesium chloride.
b) 2g of hydrochloric acid reacts with 4g of sodium hydroxide to produce 5g of sodium chloride and 1g of water.
c) 1g of lithium metal reacts with 10g of water to produce 3g of lithium hydroxide and 2g of hydrogen gas.
b) 2g of hydrochloric acid reacts with 4g of sodium hydroxide to produce 5g of sodium chloride and 1g of water.
Explain what a synthesis reaction is.
Identify what we use to determine the strength of an acid or a base.
pH scale.
List all of the physical changes from the list below:
Ice melting, burning wood, iron rusting, cutting paper, cooking an egg.
Ice melting, cutting paper.
Which state of matter is used to represent an acid dissolved in water?
Aqueous (aq).
Define the Law of Conservation of Mass.
Law of Conservation of Mass states that in a chemical reaction, mass is neither created or destroyed. The mass of the products is equal to the mass of the reactants.
Identify the type of chemical reaction below:
When exposed to heat, sodium hydrogen carbonate breaks down to water, carbon dioxide, and sodium carbonate.
Decomposition reaction.
Identify an example of an acid and describe three properties of an acid.
Any acid.
Any 3 properties of:
- sour taste
- react with metals
- corrosive
- aqueous (solutions of a compound dissolved in water)
Identify the name given to a product which is formed when two aqueous solutions react together.
Precipitate
Describe the difference between a physical change and a chemical change.
A physical change involves matter simply changing form, whereas a chemical change forms new products and is often irreversible.
Explain why we balance chemical equations.
Chemical reactions must follow the Law of Conservation of Mass, so we must make sure that the number of atoms of each element in the reactants is equal to the number of atoms of each element in the reactants.
Identify the type of chemical reaction below and balance it:
H2O ---> H2 + O2
Decomposition.
2H2O ---> 2H2 + O2
Which range on the pH scale would you expect to find bases?
Between 7 and 14, not including 7 (neutral).
You are in the science lab and come across an unknown substance. You know that the substance is sour and reacts with metals. Estimate the pH value of this substance.
Any pH between 0 and up to 7.
Describe the difference between an endothermic and exothermic reaction.
An endothermic reaction absorbs energy (usually in the form of heat), whereas an exothermic reaction releases energy (usually in the form of heat).
Describe the term 'diatomic molecule' (full points). List the 7 diatomic molecules (double points).
Diatomic molecules are two atoms of the same element bonded together.
Hydrogen, oxygen, fluorine, bromine, iodine, nitrogen, chlorine (HOFBrINCl).
When exposed to open flame, Magnesium metal (Mg) reacts with oxygen (O2) in the air to make solid Magnesium oxide (MgO).
Determine the type of reaction, and write both a worded and balanced chemical equation to represent it.
Synthesis.
Magnesium (s) + oxygen (g) ---heat---> Magnesium oxide (s).
2Mg (s) + O2 (g) ---heat---> 2MgO (s)
During a neutralisation reaction, an acid and a base react together. Describe the products formed and the pH of the resulting solution.
The products formed from a neutralisation reaction are a salt and water. The pH of the resulting solution moves towards neutral (pH 7).
Identify the reaction type of the reaction below and balance the equation:
HCl + Mg(OH)2 ---> MgCl2 + H2O
Acid-base (neutralisation) reaction.
2HCl + Mg(OH)2 ---> MgCl2 + 2H2O
Write a worded equation for the following chemical reaction:
Calcium carbonate powder reacts with a solution of hydrochloric acid to produce water, carbon dioxide, and a solution of calcium chloride.
Calcium carbonate (s) + hydrochloric acid (aq) ---> water (l) + carbon dioxide (g) + calcium chloride (aq)
Must have all correct states of matter!
Balance the following chemical equation:
NH3 + O2 ---> N2 + H2O
4NH3 + 3O2 ---> 2N2 + 6H2O
When heated, solid potassium chlorate (KClO3) breaks down into solid potassium chloride (KCl) and oxygen (O2).
Determine the type of reaction, and write both a worded and balanced chemical equation to represent it.
Decomposition.
Potassium chloride (s) ---heat---> Potassium chloride (s) + oxygen (g).
2KClO3 (s) ---heat---> 2KCl (s) + 3O2 (g).
Balance the following neutralisation reaction:
H3PO4 + NaOH ---> Na3PO4 + H2O
H3PO4 + 3NaOH ---> Na3PO4 + 3H2O
Ethanol can be used in fuel to help power cars. The combustion of ethanol (C2H5OH) in a fuel tank in the presence of oxygen produces carbon dioxide and water as by-products.
Write a balanced chemical equation to represent this reaction.
C2H5OH (l) + 3O2 (g) ---> 2CO2 (g) + 3H2O (l)