Mass.gov
Massachusetts Department of Elementary and Secondary Education
Go to Selected Program Area
Massachusetts State Seal
News School/District Profiles School/District Administration Educator Services Assessment/Accountability Family & Community  
 Student Assessment  Accountability, Partnership, & Assistance  Compliance/Monitoring >  
>
>
>
 
 
 
 
 
 
 
 
 
 
>
>
>
>
>
>
>
>

Massachusetts Comprehensive Assessment System

2011, High School Chemistry

  Question 33: Open-Response  
A student determines that a sample of an unidentified compound contains 0.8 mol sulfur and 2.4 mol oxygen. The student concludes that the chemical formula for the unidentified compound is S0.8O2.4. The student’s teacher explains that this chemical formula is not possible.
  1. Explain why the chemical formula S0.8O2.4 is not possible.
  2. Identify the most likely chemical formula for the unidentified compound, assuming that the molar ratio is correct. Show or explain your reasoning.
A second student determines that another sample contains 0.5 mol sulfur and 1.0 mol oxygen.
  1. Determine whether the two students’ samples are the same compound. Explain your answer.

Scoring Guide and Sample Student Work
Select a score point in the table below to view the sample student response.

ScoreDescription
4 The response demonstrates a thorough understanding of the law of constant composition. The response explains why the chemical formula S
0.8
O
2.4
is not possible, identifies the most likely chemical formula for the compound, and shows or explains the reasoning. The response also explains whether the two students’ samples are the same compound and explains the reasoning.
4
3
The response demonstrates a general understanding of the law of constant composition.
2
The response demonstrates a limited understanding of the law of constant composition.
1
The response demonstrates a minimal understanding of the law of constant composition.
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: Atomic Structure and Periodicity
Question 33: Atomic Structure and Periodicity
Question 44: Properties of Matter and Thermochemistry
Question 45: Bonding and Reactions

Return to the MCAS 2011 Student Work Directory



Last Updated: May 26, 2017
E-mail this page| Print View| Print Pdf  
Massachusetts Department of Elementary and Secondary Education Search · Public Records Requests · Site Index · Policies · Site Info · Contact ESE