Science Assessment ~ Topics ~ Energy: Forms, Transformation, Transfer, and Conservation ~ Item RG085003 ~ Student Performance

Potassium iodide and lead nitrate are two powders that react with each other when mixed together to form lead iodide and potassium nitrate.

Potassium iodide + Lead nitrate ---> Lead iodide + Potassium nitrate

During the reaction between these two powders, the bonds between the potassium atoms and iodine atoms are broken and bonds between lead atoms and iodine atoms form.

Which of the following describes what happens when the bonds connecting the atoms of the reactant molecules (potassium iodide and lead nitrate) break and what happens when the bonds connecting the atoms of the product molecules (lead iodide and potassium nitrate) form?

Energy is released both when the bonds of the reactant molecules break and when the bonds of the product molecules form.
Energy is required both to break the bonds of the reactant molecules and to form the bonds of the product molecules.
Energy is released when the bonds of the reactant molecules break, and energy is required to form the bonds of the product molecules.
Energy is required to break the bonds of the reactant molecules, and energy is released when the bonds of the product molecules are formed.

Distribution of responses
Answer Choice	Overall	Grades			Gender		Primary Language
	n = 1353	4–5 n = 0	6–8 n = 811	9–12 n = 542	Male n = 603	Female n = 719	English n = 1220	Other n = 98
A.	23%	N/A	24%	23%	22%	24%	23%	23%
B.	27%	N/A	27%	28%	28%	27%	28%	30%
C.	34%	N/A	34%	34%	32%	34%	34%	29%
D.	15%	N/A	15%	16%	17%	14%	15%	18%

Science Assessment

Item RG085003: During the reaction between potassium iodide and lead nitrate, energy is required to break the bonds of the reactant molecules, and energy is released when the bonds of the product molecules are formed.