The Composition of Water
What are the two atoms that make up water?
Hydrogen and Oxygen
What is a polar molecule?
A molecule that has slight positive and negative charges due to an imbalance in the way electrons are shared
In a solution made from dissolving salt in water, which component is the solvent and which is the solute?
Water is the solvent and salt is the solute
What is a hydrogen bond?
A hydrogen bond is the weak bond established between the hydrogen atoms on one molecule and the oxygen atom on another molecule
What is 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
What is the chemical formula for water?
H2O
Why can olive oil and vegetable oil mix, but not olive oil and water?
The oils are both nonpolar, and water is polar. Polar cannot dissolve non-polar
Water is sometimes known as the "near universal __________"
Solvent
Do hydrogen bonds link molecules or atoms together?
Molecules
What is surface tension?
The effect of cohesion at the surface of a liquid
What is electrolysis?
The use of electricity to break a molecule down into smaller units
Are there more protons or electrons in an individual atom?
There is an equal number of both
Water can dissolve polar substances, partially polar substances, and ____________?
Ionic compounds
Why does hydrogen bonding allow water to be a liquid at room temperature?
Hydrogen bonding causes water molecules to attract each other. Thus, causing them to remain a liquid instead of becoming a gas.
What shape does water often form because of cohesion?
Spheres or droplets
The chemical formula for sucrose (what we commonly know as table sugar) is C12H22O11. How many atoms are in this molecule?
45 atoms make up one molecule of sucrose
Draw a water molecule that demonstrates its polarity and shows which atoms have a slight positive or negative charge
Hydrogen has a slight negative charge, and the oxygens have a slight positive charge
What is an ionic compound?
Ions are atoms that have gained or lost an electron. An ionic compound is a substance made up of ions.
Draw and example of two water molecules and their hydrogen bond
The hydrogen bond connects molecules
What causes hard water?
Hard water is caused by certain ions (predominantly magnesium and calcium) being dissolved in it
The chemical formula for Red Dye 40 (the chemical dye used to color many beloved snacks like M&Ms, Skittles, Twizzlers, Fruit Loops, and Doritos) contains 18 Carbons, 14 Hydrogens, 2 Nitrogens, 2 Sodiums, 8 Oxygens, and 2 Sulfurs. What is the chemical formula for Red Dye 40?
C₁₈H₁₄N₂Na₂O₈S₂
In Experiment 4.2, why was the water supposed to bend towards the comb? (Imagine a perfectly executed experiment instead of our failed one)
Negative charge on the comb attracted the slight positive charge on the oxygen atoms causing them all to turn in the same direction towards the comb
Describe how water dissolves an ionic compound like sodium chloride?
The positive charges attract the negative charges and vice versa thus pulling apart the close packed ionic compound
Why does ice float in liquid water, and what does that have to do with hydrogen bonding?
When water is frozen in ice form, the molecules are in a rigid arrangement. When they are liquid, they can move about freely, and hydrogen bonding allows them to be closer together and thus denser.
What substance is usually put into hard water to soften it?
Sodium ions or salt