WorksheetsMod J, U3 L2
Total questions: 41
Worksheet time: 46mins
In the chemical equation 3C₂H₄, how many atoms of carbon are represented?
2
3
5
6
Which types of changes observe the law of conservation of mass?
A. only changes of state
B. only physical changes
C. only chemical changes
D. physical changes and chemical changes
Ethane, C2H6, is one of many compounds that burns in oxygen to form carbon dioxide and water.
C2H6 + O2 → CO2 + H2O
What is true of the chemical equation shown?
A. The positions of the reactants and the products are reversed.
B. The formulas of the reactants and the products are not correct.
C. The equation is not balanced, so it does not show conservation of mass.
D. The types of atoms present on the reactant side are not the same as those on the product side.
Glucose, C6H12O6, is a kind of sugar molecule. How many atoms are in a molecule of glucose?
A. 6
B. 12
C. 18
D. 24
The fuel butane, C4H10, reacts with oxygen, O2, to form water, H2O, and carbon dioxide, CO2. Which of these best describes the carbon atoms involved in this reaction?
A. The number of carbon atoms does not change.
B. Three carbon atoms are formed in the reaction.
C. Three carbon atoms are destroyed in the reaction.
D. The arrangement of carbon atoms does not change.
The model shows a single unit of a compound containing several elements. Which of these is the chemical formula for the substance?
Al₂SO₄
Al₂(SO₃)₄
Al₂(SO₄)₃
(AlO)₂(SO₄)₃
Zinc and hydrochloric acid are combined in a test tube. What can you conclude about the chemical reaction taking place? Select all that apply.
The mass of the products is exactly the same as the mass of the reactants.
One new product formed is a gas.
Molecules are changing into different molecules.
Atoms are changing into different atoms.
The photo shows the reaction between zinc and hydrochloric acid that forms zinc chloride and hydrogen gas. Which of these is a correctly balanced equation that models the reaction?
Zn + HCl → ZnCl₂ + H₂
Zn + 2HCl → ZnCl₂ + 2H₂
Zn + 2HCl --> ZnCl₂ + H₂
Zn + 4HCl --> ZnCl₂ + 2H₂
What is shown by this balanced chemical equation? Select all that apply.
H2 + Cl2 → 2HCl
The atoms in the original substances regroup and form a different substance.
The product is a new substance made up of different atoms than the reactants.
The total number of atoms changes in the reaction.
The same atoms are present before and after the reaction.
Matter is conserved.
How many oxygen (O) atoms are involved in this chemical reaction?
2Fe(OH)3 → Fe2O3 + 3H2O
12
6
3
2
What information about a molecule can you determine from its chemical formula? Select all that apply.
the number of elements in the molecule
the number of atoms of each element
the way the atoms connect to each other
the type of elements in the molecule
How does a correctly balanced chemical equation show that a chemical reaction obeys the law of conservation of matter?
The equation shows that the reactants and products are different substances.
The equation shows that atoms of the products cannot be seen.
The equation shows that the reactants and the products have the same atoms.
The equation shows that the atoms of the reactants are grouped into molecules.
What does modeling the rearrangement of atoms in a balanced chemical equation demonstrate?
Law of Conservation of Matter
New atoms are created in the product
Atoms in the reactant are destroyed
Atoms are not rearranged in a chemical reaction
What is a chemical formula?
a specific group of atoms held together by chemical bonds
A combination of chemical symbols and numbers that represents a single unit of a substance
a number below and to the right of the symbol, shows how many atoms of that element there are.
a number placed in front of a chemical formula to show how many molecules of the substance are represented in the chemical equation.
Identify the reactants.
CO₂ + 2H₂O
CH₄ + 2O₂
Identify the products.
CO₂ + 2H₂O
CH₄ + 2O₂
What is a chemical equation?
A combination of chemical symbols and numbers that represents a single unit of a substance
A specific group of atoms held together by chemical bonds.
Uses chemical formulas to model what happens in a chemical reaction.
The process in which atoms are rearranged to produce different substances
4Ca(OH)2
NaOH + HCl → NaCl + H2O
2KI + ____Cl2 → 2KCl + I2
2Al +____ HCl → 2AlCl3 + 3H2
Identify the number in blue.
Product
Reactant
Coefficient
Subscript
How many atoms of nitrogen are in the compound shown above?
1
2
3
4
What are the blue numbers called?
oxidation numbers
subscripts
group numbers
product numbers
How many molecules of KNO3 are shown?
1
2
3
4
Chemical Reaction
a substance formed as a result of a chemical reaction
a change in matter that produces one or more new substances
the process in which substances undergo chemical changes that result in the formation of new substances
a substance that enters into a chemical reaction
Chemical Equation
A representation of a chemical reaction
the starting materials in a chemical reaction
the new substances that are formed in a chemical reaction
tells how many atoms, molecules, or formula units take part in a reaction
Is the equation balanced?: 2H2O + O2 --> 4MgO + 3Fe
yes
no
