25-26 RETAKE Unit 2 Chemical Equations

1

Students perform four experiments in which they combine different substances into a beaker. Their observations are
shown in the table below.

Experiment
Action
Observation
1
Powder is added to a liquid.
Powder completely dissolves in the liquid.
2
Two liquids are combined.
A solid, white substance forms.
3
Crystals are added to a liquid.
Crystals float to the top of the liquid.
4
A solid is added to a liquid.
The solid sinks to the bottom of the beaker.

Which experiment most likely represents a chemical reaction?

Experiment 1

Experiment 2

Experiment 3

Experiment 4

1

Acetic acid is an ingredient found in vinegar and some cleaning products. The chemical formula for acetic acid
is CH₃COOH.
How many carbon atoms are represented in this formula?

1

2

3

4

1

A chemical equation in which two molecules of potassium chlorate, 2KClO₃, are decomposed results in the production of
two simpler substances. The chemical equation for this reaction is shown below.

2KClO₃ --> 2KCl + 3O₂
_{? g 24.00 g 15.78 g}
What is the mass of 2KClO₃ that is decomposed in this reaction?

39.78 g

8.72 g

63.78 g

378.78 g

Obavezno

1

Students perform four investigations. Their observations are shown in the table below.
Investigation
Action
Observation
1
Mix 50 g of baking soda and 50 mL of vinegar in a beaker.
The substance begins bubbling and produces heat.
2
Add 18 g of salt to a beaker containing 100 mL of water.
The salt completely dissolves in the water.
3
Use a straw to blow carbon dioxide into a beaker containing 20 mL of bromothymol blue solution.
The blue solution begins to lighten and eventually becomes almost clear.
4
Place a marshmallow over a candle flame.
The marshmallow turns a brownish-black color and produces an odor.
In which investigation was a physical change observed?

Investigation 1

Investigation 2

Investigation 3

Investigation 4

1

Photosynthesis is the process that requires carbon dioxide, water, and sunlight to generate glucose and oxygen. The chemical equation for photosynthesis is shown below.

6CO₂ + 6H₂O --> C₆H₁₂O₆ + 6O₂
Which statement accurately describes the atoms in the chemical equation for photosynthesis?

Calcium, oxygen, and hydrogen atoms move closer together to form new substances.

Carbon, helium, and oxygen atoms are rearranged to form new substances.

Cobalt, oxygen, and hydrogen atoms move farther apart to form new substances.

Carbon, oxygen, and hydrogen atoms are rearranged to form new substances.

1

Students performed a lab investigation on acids and bases. They recorded their observations in the table below.
Properties
Sample 1
Sample 2
Sample 3
Sample 4
Color
Clear
Clear
Yellow
Clear
Taste
Sour
Bitter
Sour
None
Ion concentration
Excess of H⁺ ions
Excess of OH^- ions
Excess of H⁺ ions
H⁺ ions = OH^- ions
Reacts with metals
Yes
No
Yes
No
Electrical conductivity
Yes
Yes
Yes
No

Based on this information, which sample most likely represents a base?

Sample 1

Sample 2

Sample 3

Sample 4

1

Which chemical equation does NOT represent the law of conservation of mass?

C₂H₆ + O₂ --> CO₂ + H₂O

HCl + NH₃ --> NH₄Cl

Ca + Cl₂ --> CaCl₂

2Fe + 3Cl₂ --> 2FeCl₃

1

The table below shows the properties of four elements.

Element Properties
Element
Luster
Melting Point
Conducts Electricity
Conducts Thermal Energy
A
Shiny
High
Yes
Yes
B
Dull
Low
No
No
C
Dull
High
Yes
Yes
D
Shiny
High
Sometimes
Sometimes
Based on this information, which element is a nonmetal?

Element A

Element B

Element C

Element D

1

The names and chemical formulas of four substances are shown in the table.

Name
Chemical Formula
Calcium carbonate
CaCO₃
Carbonic acid
H₂CO₃
Silver phosphate
Ag₃PO₄
Zinc sulfate
ZnSO₄

Which substance listed in the table is made up of the most atoms?

Calcium carbonate

Carbonic acid

Silver phosphate

Zinc sulfate

Experiment	Action	Observation
1	Powder is added to a liquid.	Powder completely dissolves in the liquid.
2	Two liquids are combined.	A solid, white substance forms.
3	Crystals are added to a liquid.	Crystals float to the top of the liquid.
4	A solid is added to a liquid.	The solid sinks to the bottom of the beaker.

Investigation	Action	Observation
1	Mix 50 g of baking soda and 50 mL of vinegar in a beaker.	The substance begins bubbling and produces heat.
2	Add 18 g of salt to a beaker containing 100 mL of water.	The salt completely dissolves in the water.
3	Use a straw to blow carbon dioxide into a beaker containing 20 mL of bromothymol blue solution.	The blue solution begins to lighten and eventually becomes almost clear.
4	Place a marshmallow over a candle flame.	The marshmallow turns a brownish-black color and produces an odor.

Properties	Sample 1	Sample 2	Sample 3	Sample 4
Color	Clear	Clear	Yellow	Clear
Taste	Sour	Bitter	Sour	None
Ion concentration	Excess of H⁺ ions	Excess of OH^- ions	Excess of H⁺ ions	H⁺ ions = OH^- ions
Reacts with metals	Yes	No	Yes	No
Electrical conductivity	Yes	Yes	Yes	No

Element	Luster	Melting Point	Conducts Electricity	Conducts Thermal Energy
A	Shiny	High	Yes	Yes
B	Dull	Low	No	No
C	Dull	High	Yes	Yes
D	Shiny	High	Sometimes	Sometimes

Name	Chemical Formula
Calcium carbonate	CaCO₃
Carbonic acid	H₂CO₃
Silver phosphate	Ag₃PO₄
Zinc sulfate	ZnSO₄

25-26 RETAKE Unit 2 Chemical Equations

Acetic acid is an ingredient found in vinegar and some cleaning products. The chemical formula for acetic acid is CH3COOH. How many carbon atoms are represented in this formula?

Photosynthesis is the process that requires carbon dioxide, water, and sunlight to generate glucose and oxygen. The chemical equation for photosynthesis is shown below.6CO2 + 6H2O --> C6H12O6 + 6O2Which statement accurately describes the atoms in the chemical equation for photosynthesis?

Which chemical equation does NOT represent the law of conservation of mass?

The table below shows the properties of four elements. Element PropertiesElementLusterMelting PointConducts ElectricityConducts Thermal EnergyAShinyHighYesYesBDullLowNoNoCDullHighYesYesDShinyHighSometimesSometimesBased on this information, which element is a nonmetal?

The names and chemical formulas of four substances are shown in the table. NameChemical FormulaCalcium carbonateCaCO3Carbonic acidH2CO3Silver phosphateAg3PO4Zinc sulfateZnSO4 Which substance listed in the table is made up of the most atoms?

Acetic acid is an ingredient found in vinegar and some cleaning products. The chemical formula for acetic acid is CH3COOH. How many carbon atoms are represented in this formula?

Photosynthesis is the process that requires carbon dioxide, water, and sunlight to generate glucose and oxygen. The chemical equation for photosynthesis is shown below.6CO2 + 6H2O --> C6H12O6 + 6O2Which statement accurately describes the atoms in the chemical equation for photosynthesis?

Which chemical equation does NOT represent the law of conservation of mass?

The table below shows the properties of four elements. Element PropertiesElementLusterMelting PointConducts ElectricityConducts Thermal EnergyAShinyHighYesYesBDullLowNoNoCDullHighYesYesDShinyHighSometimesSometimesBased on this information, which element is a nonmetal?

The names and chemical formulas of four substances are shown in the table. NameChemical FormulaCalcium carbonateCaCO3Carbonic acidH2CO3Silver phosphateAg3PO4Zinc sulfateZnSO4 Which substance listed in the table is made up of the most atoms?

Acetic acid is an ingredient found in vinegar and some cleaning products. The chemical formula for acetic acid
is CH₃COOH.
How many carbon atoms are represented in this formula?

The table below shows the properties of four elements.

Element Properties
Element
Luster
Melting Point
Conducts Electricity
Conducts Thermal Energy
A
Shiny
High
Yes
Yes
B
Dull
Low
No
No
C
Dull
High
Yes
Yes
D
Shiny
High
Sometimes
Sometimes
Based on this information, which element is a nonmetal?

The names and chemical formulas of four substances are shown in the table.

Name
Chemical Formula
Calcium carbonate
CaCO₃
Carbonic acid
H₂CO₃
Silver phosphate
Ag₃PO₄
Zinc sulfate
ZnSO₄

Which substance listed in the table is made up of the most atoms?

Acetic acid is an ingredient found in vinegar and some cleaning products. The chemical formula for acetic acid
is CH₃COOH.
How many carbon atoms are represented in this formula?

The table below shows the properties of four elements.

Element Properties
Element
Luster
Melting Point
Conducts Electricity
Conducts Thermal Energy
A
Shiny
High
Yes
Yes
B
Dull
Low
No
No
C
Dull
High
Yes
Yes
D
Shiny
High
Sometimes
Sometimes
Based on this information, which element is a nonmetal?

The names and chemical formulas of four substances are shown in the table.

Name
Chemical Formula
Calcium carbonate
CaCO₃
Carbonic acid
H₂CO₃
Silver phosphate
Ag₃PO₄
Zinc sulfate
ZnSO₄

Which substance listed in the table is made up of the most atoms?