Counting atoms
How many molecules of carbon dioxide does this formula indicate you have: 6CO2?
6
Label the following as physical or chemical changes:
a) A chain link fence rusting
b) Chopping wood into smaller pieces
a) chemical change
b) physical change
If an unbalanced force acts on an object, what will happen?
There will be some form of movement.
What is the formula for speed?
distance/time
True or False:
____ A balanced chemical equation follows the Law of Conservation of Mass.
____ The Law of Conservation of Mass applies only to chemical reactions and changes and not physical changes
T
F
How many molecules and elements are in the following formula: 8 Al(SO4)3
8 molecules
3 elements: aluminum, Sulphur, oxygen
How can you differentiate between a physical and chemical change?
physical changes do not change the composition of the substance, but chemical changes produce a new substance.
Jane pushes a sled to the right with 15 N of force, but 3 N of friction acts on the sled as she pushes. Draw a freebody diagram that shows the forces applied on the box and the net force acting on the box.
Net force: 12 N of force to the right
What is the difference for speed and velocity?
Velocity has a direction and speed doesn't.
Students mix 25 grams of baking soda with 15 grams of vinegar to observe the chemical reaction that takes place. How many grams of products would be expected?
35 grams
How many molecules, elements, and total atoms are in the following equation: 5 C6H12O6
5 molecules
3 elements: Carbon, hydrogen, oxygen
Total atoms: 120
Give an example of a physical and Chemical change (not ones listed from previous questions).
Physical: boiling water, dissolving sugar, crumpling paper
Chemical: burning wood, tarnishing silver, corroding metal
How does the mass of an object affect how it responds to a net force?
The greater the mass of an object, the more force is needed to change its motion. This means a lighter object will accelerate more easily than a heavier object if the same force is applied.
A mouse ran 25 meters in 5 seconds, stopped for 10 seconds to eat a piece of cheese, and finally ran another 5 seconds a distance of 15 meters to its home. Calculate the average speed of the mouse.
4 m/s
4Fe + 3O2→2Fe2O3
Which of the following correctly describes the chemical reaction?
a.There are 4 atoms of iron on both sides of the equation
b.There are 3 atoms of oxygen on both sides of the equation
c.There are 3 elements present on the reactants side
d.There are 4 total elements present in the equation
a. There are 4 atoms of iron on both sides of the equation
How many molecules, elements, and total atoms are in the following equation: Cu3(PO4)2
1 molecule
3 elements: copper, phosphorous, oxygen
Total atoms: 13
There are different forms of evidence that let you know a chemical reaction has taken place. What evidence of a chemical reaction occurs when fireworks explode?
Sound, heat, and light are produced.
Can an object have multiple forces acting on it but still not move? Explain.
Yes. If all the forces acting on the object are equal and opposite, they balance each other out. This means the net force is zero, so there’s no change in motion.
Two runners were competing to see who could run with a greater average speed.Runner A ran 12 miles in 4 hours. Runner B ran 9 miles in 3 hours.Which runner ran with a greater average speed? Explain.
They ran at the same speed, 3 miles per hour.
According to the Law of Conservation of Mass,is it possible for matter to be created or destroyed? Explain.
Matter cannot be created or destroyed, only changed.
How many molecules, elements, and total atoms are in the following equation: 3 Ca(ClO3)2
Molecules: 3
Elements: 3 (Calcium, chlorine, and oxygen)
Total atoms: 27
How could the process of digestion contain both physical and chemical changes? Explain your answer.
There are parts of digestion that involve physical and chemical changes. Chewing food into smaller pieces is considered a physical change. Enzymes and acid in the stomach breaking down food for absorption is a chemical change.
Why is understanding net force important in real-life situations?
It helps explain and predict motion in everyday life—like why seatbelts are needed in cars, how rockets launch, or how athletes use force to move faster or stop quickly.
Which of the following is speed and which is velocity?
a) A ball rolling 50 meters in 5 seconds
b) A person walking East at 100 meters per minute.
a) speed
b) velocity
6CO2+ 6H2O →C6H12O6+ 6O2
How many total atoms of oxygen are present on the reactants side?
36