Study Guide: Chemistry Test
This test will cover:
Law of conservation of Mass Balancing Chemical Equations
Endothermic/Exothermic Reactions Physical/Chemical Changes
Density Must know, but not on test
Concept #1 Law of Conservation Of Mass
State the law of Conservation of Mass?
Circle T/F (Regarding the law of conservation of mass) *HINT* There are 2T and 3F
T/ F The type of compound on the reactant and product side of the equation must be equal.
T/F The number of atoms of each element must be the same on the left/right side of an equation.
T/ F No new substances can be formed in a chemical reaction.
T/ F There is no relationship between the mass of the products and the mass of the reactants.
T/F The mass of the reactants must equal the mass of the products.
Concept #2 Balancing Equations:
Chemical Reactions are given the following format:
H2 + Cl2 → 2HCl
Fill in the following blanks using the word bank:
Reactants Coefficients (Multipliers) Molecules
Products Atoms Subscripts
The elements on the left hand side of the equation are called Reactants.
The elements on the right hand side of the equation are called Products.
The small numbers are called Subscripts and refer to the number of Atoms.
The large numbers are called Coefficients and refer to the number of Molecules.
*****The number of atoms of each element must be equal on both sides of this equation. You will be expected to recognize whether an equation is balanced. (Pre-AP students will be expected to balance the equations)
Tell whether the following equations are balanced… The first one is set up for you…. (If you are a Pre-AP student please add the proper coefficients to balance the equation)
AgNO3 + NaCl → 4AgCl + 2NaNO3 Yes / No
Ag __1__ Ag __4__
N __1__ N __2__
O __3__ O __6__
Na __1__ Na __2__
Cl __1__ Cl __4__
H2 + Cl2 → 2HCl Yes / No
C + O2 → 4CO2 Yes / No
Concept 3 Endothermic/Exothermic Reactions:
Absorb Hot Cold pack for injuries Release Cold Instant hot pack
Endothermic reactions Absorb heat and feel Cold.
Exothermic reactions Release heat and feel Hot.
An example of an Endothermic reaction is Cold Pack for injuries.
An example of an Exothermic reaction is Instant hot pack.
Circle Endothermic or Exothermic for the following graphs. *HINT* consider whether they
release or absorb heat.
Temperature Temperature
Concept #4 Physical/Chemical Changes:
Circle Physical/Chemical *HINT* 3 Physical/ 3 Chemical
Physical / Chemical A new substance if formed
Physical / Chemical A gas is released
Physical / Chemical A substance is melted
Physical / Chemical A substance is temporarily changed
Physical / Chemical An substance is burned and turns to Ash
Physical / Chemical A substance changes from a liquid to a solid