Chemical and Physical Changes
States of Matter
Measuring Matter
Thermal Energy and Chemical Reactions
Misc.
100
The mass of products in a chemical reaction is 50g. What was the mass of reactants? Support your answer with vocabulary.
50g Law of Conservation of Mass
100
Ice melting is an _____________ process. Support your answer by describing how energy flows.
endothermic energy is absorbed
100
Using correct significant figures: write down measurement for the following volume. /meniscus04-58b5b2e65f9b586046bb2723.png)
2.65mL
100
describe the flow of thermal energy in an endothermic reaction how does the thermal energy of the surroundings change? how does the chemical energy of the chemical compounds change?
thermal energy is absorbed by the chemical reaction thermal energy of the surroundings decreases chemical energy of the compounds increases over time
100
For the following atom, identify the atomic number and atomic mass. 
Atomic number: 20
Atomic mass: 40.078
200
What kind of change is the following: silver tarnishes
Chemical change
200
water freezing is a _________ process
exothermic energy must be released from the water molecules so that it can become a solid
200
Explain how you'd find the density of an object with an irregular shape. Why is this measurement useful?
find volume by water displacement find mass d = m/v Useful because density for a substance is constant at constant temperature and pressure. You can identify substance based on this property.
200
As written, does the following equation (combustion of methane) support the law of conservation of mass? If not, how must the equation be edited? 
No need to balance the equation so the same number of atoms are on the reactants and products sides of the equation
200
Draw a Bohr Model for the following atom (Carbon). Include protons, neutrons, and electrons on correct orbits.
300
Explain how you are able to differentiate between physical and chemical changes.
Physical change: change in state of matter/size/still same substance Chemical change: atoms rearrange to form new substances with different properties from reactants.
300
How is density affected by temperature? (hint use your understanding of water density to support your answer)
Liquid water dense than water vapor Ice less dense than liquid water (ice floats, molecules arranged in a clear pattern with some space between them.) NOTE THAT AT CONSTANT TEMPERATURE AND PRESSURE, THE DENSITY OF A SUBSTANCE IS CONTSTANT.
300
Find a ruler and measure one object on your table with correct significant digits (hint: consider your measuring tool)
answers vary
300
Describe the flow of energy in an exothermic reaction: How will the energy of the surroundings change? How will the energy of the compounds change?
energy of the surroundings will increase because thermal energy flows from the chemical reaction energy of the compounds will decrease because their chemical energy has been converted into thermal energy
300
How can you determine if two atoms will bond.
They will bond if their valence shells add up to 8 electrons.
400
List at least one example of a heterogeneous mixture and one example of a homogeneous mixture. Then explain how you are able to differentiate between the two.
Heterogeneous: salt/sand, density tower Homogeneous: soda, steel Homogenous mixtures have substances that are evenly distributed through the entire mixture.
400
What kind of energy is needed to change matter from one state to the next?
thermal energy
400
How are density and volume different?
Density = measure of mass in a space Volume = just measures the amount space an object takes up.
400
Photosynthesis and cellular respiration (breaking down of glucose) are reverse processes. Which chemical reaction is exothermic and which is endothermic?
Photosynth: endothermic Cellular resp: exothermic
400
Is the following atom likely to bond? Why or why not?
It is likely to bond because it has an incomplete valence shell (it could fit up to 2 electrons)
500
When filtering mixtures, why is it important to understand the physical properties of the substances in the mixture? Support your answer with an example.
Different properties allow you to separate out the parts of the mixture. Ex/ salt dissolves in water but sand does not. Water easily evaporates, but salt does not.This makes it easy to separate salt from sand.
500
SURPRISE GRAPHING QUESTION!!!! Draw a thermal energy/chemical energy graph for an endothermic reaction
thermal energy of the surroundings will decrease as the chemical energy increases. The total/overall energy remains the same. This is due to the law of conservation of energy
500
How are weight and mass different?
Weight = impact of gravity on a mass Mass = amount of matter in an object (does not change with gravity)
500
You put a bottle of chocolate milk in the snow. How will thermal energy flow in this scenario? What kind of process is this?
Thermal energy flows from high --> low, so thermal energy flows out of the bottle into the snow. This is an exothermic process (thermal energy leaving the milk and moving outward.) The milk will freeze. Cold is the lack of thermal energy.
*Note: this is a physical process, not a chemical reaction.
500
Is the following atom likely to bond? Explain your answer.
No. It has a complete valence shell and does not need to bond with another atom.
(other atoms include Argon, Neon, and other noble gases that have 8 electrons on their outer shell)