Science: The Laws of Conservation of Matter and Energy
Which of the processes does NOT provide evidence of a chemical change? A. Wick becomes black B. Wax becomes liquid C. Light given off D. Heat given off
B
Identify as Element (E) / Compound (C) / Mixture (M): Picture of atoms (same type) hanging around
E
What does the Law of Conservation of Matter state?
You cannot create or destroy matter, only rearrange it.
The mass of the reactants in a chemical reaction measure 20g. What must the mass of the product measure?
20g
A powder and a liquid with a total mass of 20 grams are combined in an open beaker. A reaction occurs, as indicated by the production of gas bubbles. The final mass of the solution is less than 20 grams. What best explains the difference in mass? A. Not all reactions obey the law of conservation of mass. B. Mass escaped as a gas from the open container. C. Some mass was consumed in the reaction. D. The bubbles show that mass was added to the system.
B
Mixtures are different than pure substances because mixtures- A. have lower boiling points. B. can be separated by physical means. C. are less dense than pure substances. D. contain only one type of atom.
B
Students stirred the mixtures for one minute and then recorded their observations in the table below. #1 Dissolved #2 Bubbles formed #3 Substance sank #4 Substance floated Which substance most likely caused a new substance to be formed when mixed with water? A. Substance 1 B. Substance 2 C. Substance 3 D. Substance 4
B
Which of the following changes must Hunter make to the illustration to accurately represent the same substance in the solid phase? A. There should be increased movement of the atoms. B. Atoms should be closely packed together. C. There should be very wide spaces between the atoms. D. The shape of atoms must be the shape of the container.
B
Identify as Element (E) / Compound (C) / Mixture (M): A scientist chemically combines carbon and oxygen to form CO2.
C
Identify as Element (E) / Compound (C) / Mixture (M): NaCl (Salt)
C
Identify as Element (E) / Compound (C) / Mixture (M): Picture of atoms (multiple types) bound together in arrangements
C
Identify as Element (E) / Compound (C) / Mixture (M): Sugar
C
Identify the following change as a chemical (C) or physical (P): creates a new substance
C
Identify the following change as a chemical (C) or physical (P): creates bubbles
C
Identify the following change as a chemical (C) or physical (P): flammability
C
Identify the following change as a chemical (C) or physical (P): reactivity
C
Identify the following change as a chemical (C) or physical (P): releases gas
C
Identify the following change as a chemical (C) or physical (P): rotting wood
C
When an ice cube is placed on the sidewalk on a hot day, what is the series of changes that occur to its physical state? A. Gas-> Solid-> Liquid B. Solid-> Gas-> Liquid C. Solid-> Liquid-> Gas D. Liquid-> Gas-> Solid
C
Which of the following changes must Kaylee make to the illustration to accurately represent the same substance in the gas phase? A. There should be less space between the atoms. B. Each individual atom should be larger. C. There should be very wide spaces between the atoms. D. The shape of atoms must be the shape of the container.
C
Which of the following changes must the student make to the illustration to accurately represent the same substance in the liquid phase? A. The illustration should show increased movement of the particles. B. Each individual particle should be redrawn to be much smaller. C. The space between the particles in the drawing should be made smaller. D. The shape of each particle must reflect the shape of the container.
C
What is the main difference between a physical and chemical change?
Chemical changes create a new substance while physical changes only alter the form of the substance.
Both sodium and chlorine are deadly to ingest. Salt is made of sodium and chlorine. Why doesn't salt kill you?
Chemical changes create new substances with different properties.
Matter can alter its form through a chemical change or through a physical change. No matter what the type of change is, every time matter alters its form a . . . ? A. The matter releases heat energy. B. Some of the matter is destroyed. C. New matter will be created. D. The amount of matter is the same.
D
Shauna is making breakfast for her family. During which step of preparing breakfast did Shauna observe a chemical change? A. When she cracked eggs into a bowl and they changed shape B. When she poured milk on cereal and it was no longer dry C. When she squeezed oranges and the juice came out D. When she toasted bread and it turned brown
D
Students observed rust forming on a bar of pure iron. Which of the following provides evidence that the change to the iron bar was a chemical change? A. The melting point of pure iron is approximately 1,500°C. B. The mass and the volume of the rust can be measured. C. The iron bar is able to conduct electricity even after rust forms. D. The rust is a new substance that is not pure iron.
D
Which chemical equation correctly illustrates The Law of Conservation of Matter? A. H + O2 --------> H2O2 B. H2O --------> H + O C. H3 + O2 --------> H2O2 D. H2 + O -------> H2O
D
Identify as Element (E) / Compound (C) / Mixture (M): Hydrogen
E
Identify as Element (E) / Compound (C) / Mixture (M): Li (lithium)
E
What is the difference between an exothermic and endothermic chemical change?
Exothermic reactions give off heat, endothermic get cold.
Identify as Element (E) / Compound (C) / Mixture (M): Blood
M
Identify as Element (E) / Compound (C) / Mixture (M): Fruity Pebbles
M
Identify as Element (E) / Compound (C) / Mixture (M): Picture of atoms (multiple types) hanging around in multiple arrangements
M
1. How many atoms are in the following molecule? N2F4O N= F= O=
N= 2, F=4, O=1
Identify the following change as a chemical (C) or physical (P): condensation
P
Identify the following change as a chemical (C) or physical (P): cutting bread
P
Identify the following change as a chemical (C) or physical (P): mixing Kool-Aid
P
Identify the following change as a chemical (C) or physical (P): no new substance is created
P
H2 + O --------> H2O Look at the chemical formula above. Which part of the equation represents the reactants?
Reactants- H2+O Product- H2O
When you chemically combine sodium and chlorine you get sodium chloride (salt). • What was the product in this chemical reaction? • What were the reactants?
Reactants- sodium and chlorine Product- sodium chloride (salt)
When you burn a candle you are observing both a physical and chemical change. Explain which change is physical and which change is chemical.
The burning wick is chemical while the melting wax is physical.
