Chemical Reactions Questions And Answers Flashcard

Define: chemical reaction
change of one or more substances converted into new substances
Define: reactions
substances that combine or chance
Define: products
new substances that are produced
Define: Conservation of Mass
a law which states that, in a chemical reaction, matter is not created or destroyed/stays the same
Who is Antoine Lavoisier?
He performed an experiment with mercury (II) oxide and heat.
He discovered the Conservation of Mass
Define: chemical equation
describes a chemical reaction using chemical formulas and symbols
What do chemical formulas express?
the relationship between elements in the compounds and molecules they make up
Define: coefficents
numbers which express the relationship between elements in the compounds and molecules they make up
What does knowing coefficients of chemical reactions allow chemists to do?
use the correct amounts of reactants to predict the amount of products
Define: subscripts
numbers which represent the number of atoms in a molecule of a particular element
What do the following symbols represent?
(s)
(aq)
(g)
(l)
(s) solid
(aq) aqueous- dissolved in water
(g) gas
(l) liquid
True or False?
Metals react with the atmosphere in similar ways.
False
Metals react with the atmosphere in [different] ways.
Define: balanced chemical reaction
both sides of equation have same number of atoms of each atom
How do chemists write balanced chemical equations?
(Hint: 4 step process)
1. Describe the reaction in words
2. Write the equation using formulas and symbols
3. Check for balance
4. Add coefficients where needed for balance
Define: synthesis reaction
two or more substances form a new substance
(A+B=AB)
Define: decomposition reaction
one substance breaks down into two or more substances
(AB=A+B)
Define: single-displacement reaction
one element replaces another in a compound
(A+BC=AB+C)
Define: double-displacement reaction
two metals switch places; a precipitate, water, or a gas forms when two ionic compounds in solution are combined
(AB+CD=AC+BD)
Do breaking chemical bonds require or release energy?
Require
Do forming chemical bonds require or release energy?
Release
Define: exergonic reactions
energy required to break bonds < energy released from new bonds
energy usually in the form of light
Define: exothermic reactions
energy given off in the form of heat
Define: endergonic reactions
energy released from new bonds > energy required to break bonds
no energy for the reaction to occur
Define: endothermic reactions
energy is needed in the form of heat
Define: catalyst
speeds up a chemical reaction without being permanently changed itself (does not get used up)
Define: inhibitors
prevents or slows a chemical reaction or interferes with a catalyst’s action

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