Experimental Design
A scientist keeps the amount of water, size of beaker, and room temperature the same for every trial. These are called ____
Control/controlled variables
What do you call a pure substance made of only one kind of atom?
An element
Describe the physical appearance of the molecules in a solid
Close together, in a pattern
Melting butter in a pan is an example of what type of change?
Physical
Which state of matter is shown in this picture?
https://drive.google.com/file/d/1okrEeGv5H_FgcP87-ktDT-Rxk1rx1HZu/view?usp=sharing
Liquid
This variable is the one you measure in an experiment
Dependent variable
Saltwater, lemonade, and air are examples of what?
Homogeneous mixture
Describe the physical appearance of the molecules in a liquid
No pattern, more spread out, fills shape of container
Name 2 signs of a chemical change
Bubbling, color changes, and heat
The matter in this picture is going from a _________ to a ________
https://drive.google.com/file/d/1BY617hYG0pjalvyVZsGPgaE6eQONos6O/view?usp=sharing
Liquid to a gas
In science classes, hypotheses are always written as ______________ statements
If/then/because
Define a compound
A type of matter that can be separated chemically but not physically
Describe the physical appearance of the molecules in a gas
Very spread out, fills shape of container vertically too, no pattern
Explain why rust forming on iron is considered a chemical change
Because rust is a new compound formed from a chemical reaction between iron, water, and oxygen
Does this picture show a physical or chemical change?
https://drive.google.com/file/d/1NgM-7yUMkN5vmpFoj1To2YpT-Kf8Fdzm/view?usp=sharing
In a data table showing “plant height vs. number of days,” the number of days would go on which axis?
x-axis
A material that contains visibly different substances, like sand and iron filings, is known as a...
Heterogenous mixture
Shaving cream is considered a colloid, a foam with gas bubbles mixed in a liquid solution. It has liquid and gas components.
Describe one way in which shaving cream behaves like a liquid and one way it behaves like a gas.
Liquid - flow and stick together; its particles are close enough that it holds a shape and doesn’t drift away
Gas - expand, give it low density, and allow it to be easily compressed or squished
During cellular respiration, glucose (C₆H₁₂O₆) reacts with oxygen (O₂) to produce carbon dioxide (CO₂), water (H₂O), and energy. Is this a physical change or a chemical change? Explain why.
This is a chemical change because new substances (carbon dioxide and water) are formed
Does this picture show a physical or a chemical change?
https://drive.google.com/file/d/1TdAlWR-Z4smJyjDXi9KssTVnFEXlqU_U/view?usp=sharing
Chemical
On a graph, the y-axis always shows which variable?
Dependent variable
Identify the following as an element, compound, or mixture:
- methane (CH4)
- brass (Cu and Zn)
- aluminum foil (Al)
- cereal in milk
- steam (H2O)
Compound, homologous mixture, element, heterogenous mixture, compound
Draw the molecules in a solid, liquid, and gas. For each, show the movement of these molecules using arrows (longer arrows show more movement)
Solid has a uniform shape, little movement, tightly packed together
Liquid does not have a set pattern, slightly more movement, shape of container
Gas has lots of movement, very spread out, shape of container
Identify the following scenarios as a physical (P) or chemical (C) change:
Ice cream melts on a warm day
Iron nail rusts when left outside
Salt dissolves in water
A candle burns, producing light, heat, and ash
Breaking a glass window
P, C, P, C, P
Using the information on the graph, identify the independent, dependent, and one possible control variable
https://drive.google.com/file/d/1aSIuWhB4g6qGnzxPeZO1WRfNbG6lcU9F/view?usp=sharing
Independent: number of household members
Dependent: expense on grocery
Control: time of year, city, age of household, etc.