Chemical Reactions
What is the general term for the starting substances in a chemical reaction?
Reactants
Reactions that release heat to their surroundings are called _______________ reactions.
Exothermic
H₂ + O₂ --> H₂O
2H₂ + O₂ --> 2H₂O
What name is given to the region around a charged object where it exerts an electric force?
Electric Field
What is Ohm's Law?
Voltage = Current * Resistance
What is the law of conservation of mass?
In a reaction, mass can neither be created nor destroyed. Atoms rearrange to form different materials.
The minimum amount of energy needed to start a chemical reaction is called.....
activation energy
Fe + Cl₂ --> FeCl₃
2Fe + 3Cl₂ --> 2FeCl₃
What do you call materials that allow electric charge to flow easily?
Conductors
An electric circuit with one light (resistance 10 Ω) is powered by a 20 V battery. What is the current in the circuit?
2 A
What two energy changes are signs that a chemical reaction might have occurred?
Release of light & heat.
In what type of reaction do the reactants have less energy than the products?
Endothermic
Al + HCl --> AlCl₃ + H₂
2Al + 6HCl --> 2AlCl₃ + 3H₂
What is the process of transferring electric charge from one object to another without touching?
Induction
A series circuit contains 3 resistors, the smallest resistor measures 2 Ω, the 2nd has twice the resistance & the 3rd has three times the resistance. What is the total resistance in the circuit?
12 Ω
What type of reaction involves a substance reacting with oxygen to produce heat and light?
Combustion
Specifically, how does a catalyst increase the speed of a reaction.
A catalyst reduces the activation energy in a reaction.
C₃H₈ + O₂ --> CO₂ + H₂O
C₃H₈ + 5O₂ --> 3CO₂ + 4H₂O
What do you call the safe transfer of lightning to the Earth?
Grounding
A 2 v battery powers a parallel circuit that has lights on two paths. The 1st has a resistance of 1 Ω, the 2nd 2 Ω - what is the current in the circuit?
3 A
What type of reaction is this?
BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl
Double replacement
I bake a cake & then eat it. Explain the reactions & the energy changes that occur to the bread.
Baking is an endothermic reaction — heat is absorbed & stored in the bonds on the cake. Digestion is an exothermic reaction — the energy stored in the bonds of the cake is released.
Fe₂O₃ + CO --> Fe + CO₂
Fe₂O₃ + 3CO --> 2Fe + 3CO₂
How many electrons are in 1 Coulomb?
6 × 1018 electrons
A 4 v battery powers a 2 A parallel circuit with two paths. The resistor on one path measures 6 Ω — what is the value of the 2nd resistor?
12 Ω