Chemistry - Investigations 1 & 2

1: Interactions With Water & 2: Salt And Calsium

soluble & insoluble

soluble: a solid that mixes with water

insoluble: a solid does not mix with H₂O

Miscible & Inmiscible

Miscible: A liquid that mixes with water

inmiscible: A liquid does not mix with water

Solvent

the part of a solution in the greater amount

Solute

the part of the solution in the lesser amount

Solution

a homogeneous mixture of two or more substances

(Solutions are always clear!)

Suspension

a mixture with huge particles that eventually settle out of the solvent

Colloidal dispersion (colloid)

contains solute particles that are in between the sizes of solution and suspension particles. The particles are evenly dispersed and will not settle out

homogeneous & heterogeneous

homo: mixed evenly throughout the mixture

hetero: forming different parts in the mixture

physical change

changes are reversable by physical means

chemical change

new substances are produced and the changes are irreversible by physical means

properties of water

clear, colorless, does not conduct electricity, does not change litmus

evidences of changes (chemical)

changes in temperature (not heating substance manually), bubble form, smoke, changes color, changes litmus, change in conductivity, gets cloudy, change in texture, change in smell

test for hydrogen gas

combine water and calcium and trap the escaping gas in an empty test tube. Then place a burning splint into the tube

the gas will make a popping/ whooshing noise and burn explosively

seven diatomic elements

are made of two atoms bonded together: hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine

solubility equation

ratio

percent weight change equation

(weight^f - weightⁱ) x 100

weightⁱ

What characteristics of solubility have we used to identify a solution?

If it changes litmus, if it conducts, if the solution is clear, or if the solution becomes colored

If you were given a clear, colorless, liquid, explain how you could determine if the water was a sucrose solution?

Evaporate (boil) the water and see if there is any sugar left

Explain how air can be considered as a solution

Air is a clear homogeneous mixture of many gases

Explain how air can be considered as a colloidal dispersion + give 2 examples

pollen, fog/mist, dust particles

shine a light through the mixture and see a beam

Develop a classification system to describe various ways that substances interact with water

a. some substances mix with water completely

b. some don’t mix al all

c. some mix with water partially

what evidence can be used to show that some of these materials interact (mix) with water?

a. if it disappears

b. if it changes litmus

c. if it conducts

d. if it changes the color of water

make a statement describing the extent to which the substance mixes with the water in different regions of the mixture

some substances mixed evenly throughout the mixture

what differences are there between the calcium system and the salt system relating to the interaction with water?

salt: disappeared, no change litmus, conducts, 0% weight change

calcium: bubbled, hot, cloudy white, litmus red - blue, conducts, large % weight change

what conclusions can be drawn about the interactions in these two systems?

the interactions were different: salt was a physical change and calcium was a chemical change