GC - Unit 1.5 Solutions and Energy Assessment Review

Name:__________________________

Date:_____________

Energy & Solutions Study Guide

With your group, work at your assigned study station. DISCUSS your answers with your group mates. Everyone in your group should have the same answers. Tomorrow we will be playing a game using the questions from this packet and the winner will get a prize.

Study Station 1: Molecular or Ionic?

Use the periodic table to determine if each compound is molecular or ionic. Afterwards, write down if the bonds holding the particles together are strong or weak.

A molecular compound is made up of all Non-metals.
An ionic compound is made up of and Metals and Non-Metals

Substance	Type of Compound	Bond/Force Strength
NaCl	Ionic	Weak Attraction
H2O	Molecular	Strong Bond
C6H6	Molecular	Strong Bond
CBr4	Molecular	Strong Bond
MgSO4	Ionic	Weak Attraction
NH3	Molecular	Strong Bond
CaCO3	Ionic	Weak Attraction

Study Station 2: Making a Solution Name:___________________

A solution is made up of two parts:

Solute is the substance that GETS dissolved
Solvent is the substance that is doing the dissolving

Step	Endothermic or Exothermic
The attractive forces that hold the Solute together must be broken	Endothermic; energy must be taken in and used to force the solute apart
The attractive forces that hold the Solvent together must be broken	Endothermic; energy must be taken in and used to force the solvent apart
The Solute and Solvent come together forming new attractive forces	Exothermic; the energy that was being used to hold all of the solute and solvent separate is no longer needed and it is released

Study Station #3 Name:___________________

	RbF	KBr	LiBr
Mass of substance (g)	5.0 g	5.0 g	2.5 g
Mass of water (g)	100.0g	100.0g	100.0g
Initial Temperature of Water before Dissolving (oC)	22.5oC	22.5oC	22.5oC
Final Temperature of Water after Dissolving (oC)	29.2oC	18.5oC	29.2oC

Which substance from the table above would be best to use to make an ice pack

KBr would make the best ice pack since it caused the temperature of the water to decrease

Is this substance endothermic or exothermic?

When KBr dissolved, it cause the water to lose energy and get colder. This means that the water is exothermic (it lost energy), and that KBr is endothermic since it took in the energy the water lost.

Which substance from the table above is the most exothermic per gram?

LiBr is the most exothermic per gram

How can you tell using the data in the table?

Both LiBr and RbF are exothermic (they cause the water to get warmer), but LiBr cause the same temperature change using less of the chemical. This means that per gram, LiBr releases more energy.