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Massachusetts Comprehensive Assessment System

2013, High School Chemistry

  Question 11: Open-Response  
A page from a lab notebook is shown below. The page displays data needed to find the empirical formula of a compound.
Mass of crucible, five point two three grams
Mass of crucible and iron powder, seven point four six grams
Mass of iron powder, X
Mass of sulfur added to crucible, one point two eight grams
Mass of crucible and contents after reaction, eight point seven four grams
Mass of iron-sulfur compound, Y
  1. Calculate the values for x and y. Show your calculations and include units in your answer.
  2. Assume all the iron and sulfur reacted to form an iron-sulfur compound. Calculate the number of moles of sulfur and the number of moles of iron that reacted to form the compound. Show your calculations and include units in your answer.
  3. Determine the empirical formula for the iron-sulfur compound. Show your calculations or explain your reasoning.

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 how to determine empirical formulas. The response correctly completes the data table, calculates the number of moles of each reactant, and determines the empirical formula of the product.
4
3
The response demonstrates a general understanding of how to determine empirical formulas.
2
The response demonstrates a limited understanding of how to determine empirical formulas.
1
The response demonstrates a minimal understanding of how to determine empirical formulas.
0 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: Bonding and Reactions
Question 23: Properties of Matter and Thermochemistry
Question 33: Bonding and Reactions
Question 44: Atomic Structure and Periodicity
Question 45: Solutions, Equilibrium, and Acid-Base Theory

Return to the MCAS 2013 Student Work Directory



Last Updated: June 21, 2013
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