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WorksheetsExamen Final química 2do trimestre
Total questions: 24
Worksheet time: 2hrs 0mins
Is the following equation balanced or unbalanced?
Fe + S --> FeS
Balance
Unbalance
True or False: When balancing chemical equations the subscripts can be change.
True
False
Which of the Following Correctly Balances this Equation?
_H2+_Cl2 --> _HCl
2H2 + Cl2 --> 4HCl
3H2 + 3Cl2 --> HCl
H2+Cl2 --> 2HCl
H + Cl --> HCl
When balancing equations a ____ can be placed to the left of a formula of a substance to make the equations balanced
charge
random number
subscript
coefficient
When balancing equations what does
--> mean?
subscript
forward
Just an arrow
irreversible
Which of the following is an unbalanced equation?
CaCO3 --> CaO + CO2
2Na+ 2H2O-->2NaOH + H2
PbO2 + 2H2-->2Pb + H2O
CS2 + 2O2 --> CO2 + 2SO2
Which of the following is evidence of a chemical reaction?
gases forming
water changing to ice
boiling water
paper being cut in half
What coefficient should be used to make the following equation balanced?
N2+O2--> _NO
1
2
3
4
What is a chemical equation?
A way to show a physical change using symbols.
A way to explain a chemical reaction using words
A short way to show a chemical reaction using symbols
A way to show a physical change using words.
True or False: Chemical equations use symbols instead of words to summarize chemical reactions.
False
True
The substances at the beginning of a chemical reaction are called the ____
product
chemical symbol
reagent
mole
What is the part of the chemical equation in green called?
Fe + S --> FeS
products
chemical symbols
reagents
moles
True or False: Chemical equations show how atoms are rearranged in a chemical reaction.
True
False
At the end of chemical reactions, what is the total mass of the reactants compared to the total mass of the products?
the product is doubled
the product is half the mass of the reactants
the mass changes depending on the reaction
the mass is the same
How many atoms of aluminum are on each side of the following equation: 4Al + 3O2 --> 2Al2 O3
1
2
4
6
Why is the following chemical equation not balanced?
H2 + O2 --> H2O
each side of the equation has a different number of hydrogen atoms
each side of the equation has a different number of oxygen atoms
each side has the same mass
How many carbon atoms are present in this chemical formula? 4 Sn(C2H3)3
8
2
24
20
The Law of Conservation of Mass states
That atoms can be created or destroyed in a chemical reaction.
You can have unequal amount of atoms on both sides of a chemical equations
That conserving energy is important.
That atoms can not be created nor destroyed in a chemical reaction.
What do coefficients tell us in a chemical formula?
How many atoms present.
How much electrons present.
How many molecules present
Only the amount of atoms of the element it come before.
What so subscripts tell us about a chemical formula?
How many molecules present.
How many individual atoms present of the element they come before.
How many individual atoms present of the elements they come after
If the molecule is stable or not
What type of change is usually not easily reversed?
Chemical Change
Physical Change
Which of the following are not indicators of a chemical change taking place?
Gas given off
Temperature change
Precipitate formed
A substance dissolving
If we have 1000 gr of He, 1000 gr Na and 1000 gr of O2. In which element we have more moles?
He = 4 gr/ mole
Na= 23 gr/ mole
O= 16 gr/ mole
Following the law of conservation of matter
N2 + O2 → NO
How many grams we have in the products?
