Massachusetts Comprehensive Assessment System

2012, High School Chemistry

Question 33: Open-Response

Reporting Category: Bonding and Reactions
Standard: 5.1 - Balance chemical equations by applying the laws of conservation of mass and constant composition (definite proportions).
Standard: 5.2 - Classify chemical reactions as synthesis (combination), decomposition, single displacement, double displacement, and combustion.

Five chemical reactions are listed in the table below.

Reaction 1	CaCO3 → CaO + CO2
Reaction 2	Ca(OH)2 + 2HCl → CaCl2 + 2H2O
Reaction 3	NH3 + HCl → NH4Cl
Reaction 4	PbO2 → Pb + O2
Reaction 5	2Mg + O2 → 2MgO

Identify one chemical reaction from the list that is a synthesis (combination) reaction. Explain why you identified this reaction as synthesis.
Identify one chemical reaction from the list that is a decomposition reaction. Explain why you identified this reaction as decomposition.
Describe a combustion reaction.
Write a balanced chemical equation for a combustion reaction using some or all of the substances from the table below.

C3H8	CO2
O2	H2
C	H2O

Scoring Guide and Sample Student Work

Select a score point in the table below to view the sample student response.

Score	Description
4	The response demonstrates a thorough understanding of how to classify chemical reactions. The response correctly identifies one example of a synthesis (combination) reaction and one example of a decomposition reaction and clearly explains each answer. The response also correctly describes a combustion reaction and gives a balanced chemical equation for a combustion reaction.
4
3	The response demonstrates a general understanding of how to classify chemical reactions.
2	The response demonstrates a limited understanding of how to classify chemical reactions.
1	The response demonstrates a minimal understanding of how to classify chemical reactions.
0	The response is incorrect or contains some correct work that is irrelevant to the skill or concept being measured.

Note: There are 2 sample student responses for Score Point 4.

High School Chemistry

Question 11: Solutions, Equilibrium, and Acid-Base Theory

Question 23: Properties of Matter and Thermochemistry

Question 33: Bonding and Reactions

Question 44: Atomic Structure and Periodicity

Question 45: Bonding and Reactions

Return to the 2012 MCAS Sample Student Work: High School Chemistry

Last Updated: August 9, 2021