Module 4 Study Guide Flashcards
Electrolysis
Using electricity to break a molecule down into its constituent elements
Polar molecule
A molecule that has slight positive and negative charges due to an in balance in the way electrons are shared
Solvent
A liquid substance capable of dissolving other substances
Solute
A substance that is dissolved in a solvent
Cohesion
The phenomenon that occurs when individual molecules are so strongly attracted to each other that they tend to stay together even when exposed to tension
Hard water
Water that has certain dissolved ions in it, predominantly calcium ions
Suppose you did an electrolysis experiment like in experiment 4.1 on hydrogen peroxide, whose chemical formula is H202. Which of the following results would you expect: (a) same as with water, (b) equal amounts of hydrogen and oxygen, or (c) twice as much oxygen as hydrogen.
(B) equal amounts of hydrogen and oxygen
Supposed you performed experiment 4.1 with a test tube which had a crack in it. Gas could slowly leak out that crack, but not nearly as quickly as it was being made in the experiment. Suppose further that the crack was in the test tube which held hydrogen gas. Which chemical formula might result from such a botched experiment: HO or H4O?
HO
Epsom salts, which you used in experiment 4.1, have the chemical formula of MgSO4. If Mg is the symbol for magnesium, S stands for sulfur, and O represents oxygen, how many of each atom are in a molecule of Epsom salts?
1 Magnesium
1 Sulfur
4 Oxygen
Calcium carbonate is an ionic substance that is commonly called “chalk”. If this molecule has one calcium atom (Ca), one carbon atom (C), and three oxygen atoms (O), what is its chemical formula?
CaCO3
One of the most common household cleaners is ammonia, whose chemical formula is NH3. How many atoms are in a molecule of ammonia?
4
A molecule is comprised of atoms that all pull on electrons with the same strength. Will this molecule be polar?
Yes, this molecule is polar.
Baking soda dissolves in water. Will it dissolve in vegetable oil, which is a nonpolar substance?
No, because only nonpolar substances can dissolve in nonpolar solvents. And because baking soda dissolves in water we know it isn’t nonpolar.
Carbon tetrachloride will not dissolve in water. Is it made up of ionic molecules, polar molecules, or nonpolar molecules?
Carbon tetrachloride is made up of nonpolar molecules.
Suppose you were able to count the molecules in a substance. Which would have more molecules, one liter of liquid water or 1 liter of ice?
1 liter of water
