Question

matter

1. three students made multiple weighings of a copper - cylinder, each using a different balance. describe the accuracy and precision of each students weighings if the correct mass of the cylinder is 47.42.

	colin	tamika	river
weighing 2	47.04	47.30	47.01
weighing 3	46.83	47.42	47.09
weighing 4	47.47	47.41	47.93

physical and chemical changes and properties

1. classify each of the following as a physical (phy) or chemical (chm) property:

a) boiling point _
b) rust _
c) flammability _
d) bending _
e) deformation _
f) decomposition _
g) melting point _
h) reactive with acid _
i) density _

1. classify each of the following as a physical (phy) or chemical (chm) change:

a) corrosion _
b) explosion _
c) evaporation _
d) rotting of food _
e) mixing _
f) melting _
g) grinding _
h) burning _
i) dissolving _

1. is a change in state of matter a (a) physical change (b) chemical change
2. compounds can be separated into their components by physical change (a) true (b) false
3. what is the difference between endothermic and exothermic?
4. which of the following is an exothermic physical change? choose the best answer:

a. boiling water b. water vapor condensing
c. a cake baking d. bread toasting

1. which of the following is an endothermic chemical change? choose the best answer:

a. a cake baking in the oven b. chocolate melting in a microwave
c. frozen strawberries pulverized in a blender d. paper burning

1. which of the following is true of an exothermic physical change? choose the best answer:

a. the substance feels hot, and new substances are created.
b. the substance feels cool and new substances are created.
c. the substance feels hot and no new substances are created.
d. the substance feels cool and no new substances are created.

1. classify each of the following as: element, compound, homogeneous mixture, or heterogeneous mixture

a) air _
b) h₂o _
c) iron filings _
d) kool - aid _
e) a salad _
f) sodium chloride _

Explanation:

Step1: Recall physical and chemical property definitions

Physical properties can be observed or measured without changing the substance's identity. Chemical properties involve a change in the substance's identity.

Step2: Classify properties in question 10

a) Boiling point - PHY (Observed without changing substance)
b) Rust - CHM (Iron changes to iron - oxide)
c) Flammability - CHM (Substance burns, changes identity)
d) Bending - PHY (Shape changes, identity remains)
e) Deformation - PHY (Shape change, no chemical change)
f) Decomposition - CHM (Substance breaks into other substances)
g) Melting point - PHY (Observed without changing substance)
h) Reactive with acid - CHM (Chemical reaction occurs)
i) Density - PHY (Measured without changing substance)

Step3: Recall physical and chemical change definitions

Physical changes do not change the substance's identity, while chemical changes result in new substances.

Step4: Classify changes in question 11

a) Corrosion - CHM (Metal changes to metal - oxide)
b) Explosion - CHM (Often involves chemical reactions)
c) Evaporation - PHY (Change of state, no new substance)
d) Rotting of food - CHM (Microbial - induced chemical change)
e) Mixing - PHY (If no chemical reaction, just combination)
f) Melting - PHY (Change of state, no new substance)
g) Grinding - PHY (Size change, no chemical change)
h) Burning - CHM (Substance reacts with oxygen, new substances formed)
i) Dissolving - PHY (If no chemical reaction, just dispersion)

Step5: Answer question 12

A change in state of matter is a physical change. So the answer is A. True

Step6: Answer question 13

Compounds can be separated into their components by chemical change, not physical change. So the answer is B. False

Step7: Recall endothermic and exothermic definitions

Endothermic processes absorb heat, exothermic processes release heat.

Step8: Answer question 15

Exothermic physical change - Water vapor condensing releases heat and is a physical change. Answer is B.

Step9: Answer question 16

Endothermic chemical change - A cake baking in the oven involves chemical reactions and absorbs heat. Answer is A.

Step10: Answer question 17

In an exothermic physical change, the substance feels hot and no new substances are created. Answer is C.

Step11: Recall element, compound, homogeneous and heterogeneous mixture definitions

Elements are pure substances with one - type of atom. Compounds are pure substances with two or more types of atoms chemically combined. Homogeneous mixtures have uniform composition, and heterogeneous mixtures have non - uniform composition.

Step12: Classify substances in question 18

a) air - HOMOgeneous mixture (Mixture of gases with uniform composition)
b) H₂O - COMPound (Two types of atoms chemically combined)
c) Iron filings - ELement (Pure iron)
d) Kool - Aid - HOMOgeneous mixture (Dissolved in water uniformly)
e) A salad - HETEROgeneous mixture (Non - uniform components)
f) Sodium chloride - COMPound (Sodium and chlorine chemically combined)

Answer:

10a) PHY
10b) CHM
10c) CHM
10d) PHY
10e) PHY
10f) CHM
10g) PHY
10h) CHM
10i) PHY
11a) CHM
11b) CHM
11c) PHY
11d) CHM
11e) PHY
11f) PHY
11g) PHY
11h) CHM
11i) PHY

1. A. True
2. B. False
3. B. Water vapor condensing
4. A. A cake baking in the oven
5. C. The substance feels hot and no new substances are created.

18a) HOMOgeneous mixture
18b) COMPound
18c) ELement
18d) HOMOgeneous mixture
18e) HETEROgeneous mixture
18f) COMPound