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WorksheetsChemistry Unit review
Total questions: 38
Worksheet time: 31mins
In this chemical equation, the elements in red are the_______.
Products
Reactants
Subscripts
Coefficients
Sugar is added to water, and the mixture is stirred. What type of mixture has been created?
A homogeneous mixture.
A plain mixture.
A heterogeneous mixture.
A complex mixture.
A chemist is looking for an element that reacts similarly to the element lithium (Li). What would you tell the chemist to look for on the periodic table?
Look for similarities in the mass. Elements in groups will act the same as other elements in the group.
Look for any metal.
Its neighbor to the bottom (sodium) has similar properties to lithium because trends in groups behave very similarly to each other.
Nothing is similar
Which of the following elements is the most reactive?
strontium (Sr)
calcium (Ca)
beryllium (Be)
magnesium (Mg)
Which best describes the reactivity of metals when moving from left to right on the periodic table?
The reactivity remains the same.
They become more reactive.
They become less reactive.
The reactivity remains the same.
Which element in Period 3 is known to be a highly reactive metal?
argon (Ar)
sulfur (S)
scandium (Sc)
sodium (Na)
What do the atomic numbers represent?
number of atoms
number of protons
number of neutrons
number of protons plus neutrons
Which is the best evidence of a chemical change occurring when bread is baked?
The bread is warm and soft.
Steam rises from the bread after it is baked.
The dough rises during baking, and its texture changes.
The loaf of bread appears exactly the same before and after baking.
Which best represents a physical property of a substance?
Acids act as a corrosive to metal.
Gold has a density of 19.3 g/cm .
Sodium combines with chlorine to create sodium chloride.
Hydrochloric acid reacts with zinc metal, creating hydrogen gas.
A chemical reaction separates water into hydrogen gas and oxygen gas. Which of the following statements is true about the mass of the water and the combined mass of the two gases?
Hint: Think about the conservation of mass problems that we did in class. We have a product, in this case it is water and hydrogen gas , and the reactant, in this case it is the oxygen gas. There needs to be the same amount of each element on both sides of the equation to balance.
The mass of the water is greater than the combined mass of the two gases.
The combined mass of the two gases is much greater than the mass of the water.
The combined mass of the two gases is the same as the mass of the water.
The mass of the water is the same as double the combined mass of the two gases.
The chemical equation below shows reactants and products.
6CO2+12H2O+light+enzymes→ C6H12O6+6O2+ 6H2O
Which statement is BEST supported by analyzing this equation? Hint: A new substance is made after the products go through a chemical reaction.
CO2 is made from the chemical reaction.
No new compounds are made from this reaction.
O2, oxygen gas, is needed to make the reaction start.
The atoms rearrange in the chemical reaction so that C6H12O6, glucose, is made.
Sodium sulfate and barium chloride react with each other to form sodium chloride and barium sulfate.
Which statement MOST accurately describes the mass of the reactants compared to the mass of the products? Hint: Each element has a specific mass. The Law of conservation of mass states that the product must equal the reactant. This means that the mass of both the product and the reactant must be equal.
The mass of the reactants is the same as the mass of the products
The products have a greater mass because matter was created during the reaction.
The reactants have a greater mass because some of the mass was converted to heat
The reactants have a greater mass because some matter was destroyed by the reaction.
If 100 grams of vinegar and 5 grams of baking soda are poured in a container, a small amount of gas will be produced. What will the final mass of the products be if the gas is trapped in the container? Hint: The law of Concervation of mass states that the the product must equal the reactant.
100 grams
104 grams
105 grams
110 grams
Which of these does NOT illustrate substances reacting to form new substances? Hint: Which one is not balanced?
H2O(liquid)→H2O(gas)
2H2+O2→2H2O
2Na + Cl2→2NaCl
6CO2+6H2O→C6H12O6+6O2
During photosynthesis, carbon dioxide and water combine according to the general equation:
Carbon Dioxide + Water = Sugar and Oxygen
Why is photosynthesis a chemical reaction?
because new substances are formed
because an input of energy is required
because the reactants are compounds
because the products include an element
Which of these must occur when a substance goes through a chemical change?
The substance gets larger
The substance changes phases.
The substance changes shape.
The substance forms a new substance.
What is formed when a sodium atom and chlorine atom react chemically?
an element
a compound
an electron
a neutron
A student studies four chemicals in a laboratory investigation.
1 Salt NaCl
2 Water H2O
3 Iron Fe
4 Limestone CaCO3
Which chemical cannot be further broken down into other chemicals using ordinary laboratory processes?
1
2
3
4
Calcium carbonate (CaCO3) is considered a compound because it is made up of two or more
elements
molecules
gases
solids
Elements in the Periodic Table of the Elements are organized into columns and rows.
The columns are organized to show the
similarities of the reactivity in groups.
number of neutrons in a column.
sum of atomic weights per column.
amount of radioactivity in each group.
What is the significance of an element's increasing atomic mass on the periodic table?
A repetition occurs in chemical and physical properties.
An atomic weight corresponds to the existing abundance
The number of neutrons and protons.
The chemical compounds formed by the elements increased by one.
Elements in the same column of the Periodic Table of the Elements all
have the same number of protons.
share the same atomic structure.
have similar physical characteristics.
have similar masses.
Which characteristic of an element determines its placement in the periodic table?
mass
size
number of neutrons
number of protons
Which statement BEST describes the organization of the Periodic Table of the Elements?
All gases are grouped together
Gases easily form compounds with other elements.
Elements within a group have similar properties.
Elements within a period have the same number of electrons.
When burning methane gas, which outcome best demonstrates the law of conservation of mass? Hint: The equation is balanced.
CH4 → CO2 + H20
CH4 + O2 → CO2 + 2H20
CH4 + O2 → 2CO2 + 2H20
CH4 + 2O2 → CO2 + 2H20
Which is true of a chemical equation?
Products and reactants must be balanced
Subscripts must be used with all products and reactants.
Energy must be included in the beginning of the reaction.
Coefficients must be used with all products and reactants
The following chemical reaction occurs.
2H2O → 2H2O + O
How many atoms of hydrogen are involved in the reaction?
Hint: How many Hydrogen on 1 side.
1
2
4
8
Which chemical reaction supports the law of conservation of mass?
Hint: Which equation is balanced?
H2O → H2 + O2
H2O2 → 2H2 + O2
H2O2 → H2 + 2O2
2H2O → 2H2 + O2
Which best explains why conservation of mass should be studied in a closed system? (Closed systems prevent any loss of matter.)
Hint: You don't want any loss of matter so your product and reactant will be balanced.
to prevent the loss of any reactants
to prevent contamination of the products
to prevent the release of any gases produced
to prevent the absorption of heat from the outside
Which demonstrates a chemical change?
water + salt = saline solution
white sugar + clear acid = black solid
water + blue food coloring = blue solution
red food coloring + yellow food coloring = orange solution
Which best represents a physical property of a substance?
Acids act as a corrosive to metal.
Gold has a density of 19.3 g/cm .
Sodium combines with chlorine to create sodium chloride.
Hydrochloric acid reacts with zinc metal, creating hydrogen gas.
Which is the best evidence of a chemical change occurring when bread is baked?
The bread is warm and soft.
Steam rises from the bread after it is baked.
The dough rises during baking, and its texture changes.
The loaf of bread appears exactly the same before and after baking.
