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.
Change in color, gas formation (bubbling), precipitation formation (solid forms), change in temperature, change in odor
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
Chemical
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
Define state of matter.
A state of matter is a general category that matter can take. This can be a solid, liquid, or gas.
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, homogeneous mixture, element, heterogeneous mixture, compound
Define phase of matter.
A phase of matter is a specific region of matter with uniform properties. One state of matter can contain multiple phases of matter.
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
A candle burns, producing light, heat, and ash
Breaking a glass window
Physical, Chemical, Chemical, Physical
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.