Honors Chemistry Semester One Final
A 15.75-g piece of iron absorbs 1086.75 joules of heat energy, and its temperature changes from 25°C to 175°C. Calculate the specific heat capacity of iron.
0.46 J/gxoC
Standard conditions of temperature and pressure are
0C and 101 kPa
0.000000001
1
10
1
10,000
1
1000
1
How many bars do we usually use for cold objects?
1 bar
How many bars of energy do solids have?
1 bar
Explain why the alcohol level in a thermometer falls when it is placed in a cooler fluid. (3-step process)
1.) Energy from the thermometer is transferred in the cooler fluid. 2.) This transfer of energy causes the alcohol molecules to slow down. 3.) The alcohol molecules move closer together so that the height of the alcohol in the tube decreases.
Explain why the alcohol level in a thermometer rises when it is placed in a warmer fluid. (3-step process)
1.) Energy from the warmer fluid is transferred to the alcohol in the thermometer. 2.) This energy causes the alcohol molecules to move faster. 3.) The alcohol molecules move further apart and this expansion is noted by alcohol rising in the tube.
The temperature of an unknown piece of metal with a mass of 30.00 g changes from 25.0 °C to 35.0 °C when the metal absorbs 350.0 J of energy. What is the specific heat of the metal?
1.17 J/g°C
1,510,295,764
10
If I heat up 2 pans of water one has 100 mL in it and one has 1000mL. Which one heats up the fastest?
100 mL
103.45 + 2 =
105
17,000,200,023
11 13
440,567,395,789
12
The specific heat(c) of copper is 0.39 J/g °C. What is the temperature change(∆t) when 100 Joules of heat(Q) is added to 20 grams?
12.82 °C
170,900,002,000.0
13
What is the volume of 150 grams of lead if it has a density of 11.3 g/cm3?
13 cm3
Given an atmospheric pressure of 1.85 atm, what would be the pressure in mmHg?
1406 mmHg
The students measured length during a science experiement, they got 12.00 cm. But the actual measurement was 14.25 cm. What was the percent error?
15.79%
Convert -89 C to K
184K
0.000031
2
How many bars do we usually use room temperature?
2 bars
How many bars of energy do liquids have?
2 bars
A sample of iron receives 50.J of heat energy that raises the temperature of the iron 25.0°C. If iron has a specific heat of 0.10 J/g°C, what is the mass of the iron sample?
20 g
If a piece of aluminum is heated from 30.0oC to 50.0oC, what is the value of ΔT?
20o C
Convert 300 K to C
27 C
What is the formula for Kelvin?
273 + C degrees
What is zero degrees Celsius converted to Kelvin?
273 K
How many Joules of energy are required to change 10 gram of liquid water from 20 C to 90 C?
2926 J
How many joules of heat are needed to raise the temperature of 10.0 g of aluminum from 22°C to 55°C, if the specific heat of aluminum is 0.90 J/gx°C?
297 Joules
What temperature in Kelvin is room temperature?
298 K
0.00707
3
Calculate the heat absorbed by 105.0 grams of water when it is heated to cook spaghetti. The initial temperature of the water is 20.0°C, and the final temperature of the water is 99.0°C. The specific heat of water is 4.18 J/g•°C.
34673 J/g°C
What is the boiling point of water in Kelvin?
373 K
0.7801
4
How many bars of energy do gases have?
4 bars
You have 20 g of water with specific heat of 4.18 J/g°C. The temperature changes from 25° C to 20° C. How much heat energy (Q) moves from the water to the surroundings?
418 J
The volume of a gas is increased from 150.0 mL to 350.0 mL by heating it. If the original temperature of the gas was 25C, what will its final temperature be (in C)
422 C
0.0044625
5
When the external pressure is 505 kPa, what is the vapor pressure of water at its boiling point?
505 kPa
When a piece of aluminum foil is taken out of the oven and cools from 100° to 50°, What is the change in temperature?
50°
A 0.3 g piece of copper is heated and fashioned into a bracelet. The amount of energy transferred by heat to the copper is 66,300 J. If the specific heat of copper is 390 J/g 0C, what Is the change of the copper's temperature?
566.7 °C
100,002
6
A material was cooled from 100ºC to 40ºC. What is the temperature change?
60ºC
120,000.1
7
14,000,001
8
If the specific heat of water is 4,186 J/kg∙°C, how much heat is required to increase the temperature of 1.2 kg of water from 23 °C to 39 °C?
80,371.2 J
440,022,001
9
Scientific Method
A logical approach to solving problems by observing and collecting data, formulating hypotheses, testing hypotheses, and formulating theories that are supported by data
Weight
A measure of the force of gravity on an object, and amount of matter
Hypothesis
A testable prediction, often implied by a theory
Constant
A value that does not change
If heat is released by a chemical system, an equal amount of heat will be
Absorbed by the surroundings
Percent error formula
Accepted value-measured value| / accepted value x100
Winds are caused by differences in _____.
Air pressure
How does heat flow?
Always from hot to cold
Explain how the Celsius scale was devised and why it is not appropriate to use it when describing the behavior of gases.
Anders Celsius used a tube of mercury, marking the height of the mercury column when he placed the tube in an ice bath at 0c; he placed it in boiling water bath and called that 100c. He marked it literally between 0 and 100c.
1045
Any zero trapped between any 2 significant numbers are significant
Matter
Anything that has mass and takes up space
According to the kinetic-molecular theory, collisions between molecules in a gas
Are perfectly elastic
What happens to the rates of condensation and evaporation if the temperature increases?
At first, there will be more evaporation and then there would be more particles which would lead to more condensation until it leads to a new equilibrium.
Where is the air pressure the greatest on a mountain?
At the bottom of the mountain
Where is the density of the air the greatest on a mountain?
At the bottom of the mountain
The temperature at which the motion of particles theoretically ceases is what?
0 K
What is known as absolute zero?
0 K
What is the instrument used to measure air pressure?
Barometer
Parts of a Bunsen Burner
Barrel, collar, air holes, gas intake, gas valve, stand
When the vapor pressure of a liquid is equal to the atmospheric pressure, the liquid begins to do what?
Boil.
When the atmospheric pressure equals the equilibrium vapor pressure ___ occurs.
Boiling
How are conditions of pressure and temperature, at which two phases coexist in equilibrium, shown on a phase diagram?
By a line separating the phases.
Random
By chance, not planned or prearranged; irregular
What is a device used to measure the heat absorbed or released during a chemical or physical change?
Calorimeter
What is temperature measured in?
Celcius, Kelvin, Farenheight
This most widely used temperature scale is based on the freezing and boiling points of water.
Celsius
Extensive
Change based on size/shape
Intensive
Change based on substance
E(ch) is what?
Chemical energy
What causes gas pressure?
Collisions of molecules with the walls of containers
If the decimal point is present
Come from pacfic (go right)
A physical change from gas to liquid is called....
Condensation
This part of the experiment serves as a basis of comparison; the one variable being tested has been omitted.
Control group
Infinite sig figs
Counting
The symbol for specific heat is .......
Cp
Qualitative
Data in the form of recorded descriptions rather than numerical measurements.
Quantitative
Data that is in numbers
As you climb up a mountain what happens to the air pressure?
Decreases
At a constant pressure, the volume decreases. What happens to the temperature?
Decreases
As atmospheric pressure decreases, the column of mercury in a barometer does what?
Decreases in height.
Who is Democritus and what did he do?
Democritus was an Ancient Greek philosopher and was the first person to propose that matter is made of atoms (little particles) which happened 2,000 years ago.
Change from Gas to Solid is called.......
Deposition
Law
Describes what will happen
What is Diffusion?
Diffusion is when something spreads out (red and blue liquid lab).
What are examples of things that go from a solid to a liquid?
Dry ice
Is it hard or easy to evaporate liquids with weak inter molecular forces?
Easy
A process that absorbs heat is called an
Endothermic process
Kinetic Energy means...
Energy that a particle possesses by virtue of being in motion.
What is it called when the rate of condensation equals the rate of evaporation?
Equilibrium (there is no net change which means that it is stable).
Use factors to calculate the new P, V, or . Make a decision as how to the change affects the variable that you are looking for.
Examples; If a pressure doubles, the volume will halve. If the temperature doubles, the pressure will double. If the temperature triples, volume will triple.
The height of Hg in a barometer is the same whatever the location and weather conditions.
False
What happens to the oxygen molecules as altitude increases?
Fewer molecules
What phase of matter is shown in the diagram? (The particles are far apart and have lots of energy.)
Gas
Which state of matter is easily compressed?
Gas
Gas pressure is caused by what?
Gas molecules colliding with surfaces
Small molecules are usually at what state at room temperature?
Gases
What state of matter has the most energy?
Gases
What state of matter is at the highest amount of energy?
Gasses
Q=mH(f)
H(f) is the heat of fusion, melt or freeze
Q=mH(v)
H(v) is the heat of vaporization, boiling or condensing
What is energy being transferred as?
Heat
Endothermic
Heat is absorbed (inside)
Exothermic
Heat is released (outside)
How must energy flow into a system?
Heating
How does the temperature effect diffusion (red and blue liquid lab)?
Hotter particles collide with each other and diffuse into the water faster than the colder ones do (hotter object always transfers to the colder object).
Accuracy
How close a measurement is to the true value
Precision
How specific/consistent
Using the heat equation, what would the formula look like if we were solving for change in temperature?
Q / (m Cp) = ∆T
During a phase change, the temperature of a substance
Remains constant
Students make ice cream to investigate matter and its properties. The students add salt to the ice cream maker so that the mixture will change from a liquid to a solid. Which conclusion provides the most important reason salt is used to make ice cream solidify?
Salt lowers the freezing point of water.
Systematic
Same direction of error
As particles are exposed to colder temperatures they _____.
Slow down
What are particles in a gas best described as?
Small, hard spheres with insignificant volumes.
Particles in a _____________ are tightly packed together.
Solid
Which state of matter has a fixed shape?
Solid
Freezing goes from what state to what state?
Solid to liquid
What state of matter is at the lowest amount of energy?
Solids
Why do some molecules evaporate?
Some molecules have enough energy to break free from the old of its neighboring molecules to evaporate
A chunk of ice whose temperature is -20C is added to an insulated cup filled with water at 0C. What happens in the cup?
Some of the water freezes, so the chunk of ice gets larger
The amount of energy required to raise the temperature 1ºC for every kilogram is called____?
Specific Heat
The heat required to raise the temperature of a SUBSTANCE by 1∘C
Specific Heat
As particles are exposed to warmer temperatures they...
Speed up
What does STP stand for?
Standard Temperature and Pressure
If the decimal point is absent
Start counting digits from the Atlantic (right) side, starting with the first non-zero digit, then go left
The lower the boiling point, the stronger or weaker the inter molecular forces?
Stronger
Example of an endothermic phase transition
Sublimation
The direct change of a substance from a solid to a gas is called what?
Sublimation
What is it called when a solid turns directly into a gas?
Sublimation
Chemical
Substance, matter that has a definite and uniform composition
The speed of the molecules determines the _____.
Temperature
What affects gas pressure?
Temperature, volume, number of particles, and the amount of gas
What does the slope of a line tell you (y axis is volume in mL and x axis is volume in cm3)
That for every one cm3 the volume increases by the slope
What is the basis for the Kelvin temperature scale (how was it created and why do we need to use it)?
The Kelvin scale does not have negatives which shows the change between the initial and the final temperature.
Heat of Vaporization
The amount of heat required to boil 1 g of a substance at its BP
Heat of Fusion
The amount of heat required to melt 1 g of a substance at its MP
Mass
The amount of matter in an object
Volume
The amount of space an object takes up
How does the atmospheric pressure at altitudes below sea level compare with atmospheric pressure at sea level?
The atmospheric pressure below sea level is higher.
What happens to the average kinetic energy of the particles in a sample of matter as the temperature of the sample is increased?
The average kinetic energy increases.
Temperature
The average kinetic energy of particles
Consider an iron cube and an aluminum cube. If the two cubes were at the same temperature, how would the average kinetic energy of the particles in iron compare with the average kinetic energy of the particles in aluminum?
The average kinetic energy of the aluminum particles would be greater.
As the temperature of the gas in a balloon decreases, what happens?
The average kinetic energy of the gas decreases.
What does temperature determine?
The direction of heat flow
Independent variable
The experimental factor that is manipulated; the variable whose effect is being studied.
What is Q?
The heat that is transferred to the surrounding objects
Multiplying and dividing with sig figs
The least amount of sig figs
Do the molecules evaporate when you put a lid on a cup of water?
The molecules do not stop evaporating, but it instead bounces and periodically a vapor molecule that is moving slowly will bump in the water surface and stick. This is called condensation.
What are the water vapor molecules doing inside of the cup and what is it called?
The molecules exert a vapor pressure on the sides of a cup.
How does increasing the amount of salt added to the ice affect the freezing and melting points of water?
The more salt, the lower the freezing and melting points of water.
What is pressure?
The number of collisions and how hard the particles are colliding.
The pressure exerted by a gas in a container depends on what?
The number of collisions between gas molecules and the walls of the container.
What water molecules evaporate?
The ones at the surface and are moving fast enough
Dependent variable
The outcome factor; the variable that may change in response to manipulations of the independent variable.
How does a thermometer measure the temperature of an object?
The particles from the object collide and cause the glass to heat up (heat transfer), the glass particles begin to vibrate faster so it collides with the particles in the alcohol.
An inflated balloon is placed in a refrigerator. Which statement describes the movement of the gas particles in the balloon?
The particles move more slowly and become closer together.
What statements are part of the kinetic molecular theory?
The particles of a gas move independently of each other, move rapidly, and are relatively far apart,
Which is moving faster, the water vapor or the liquid water if the room is equal to 25 °C, the vapor is equal to 25 °C, and the water is equal to 25 °C?
They are the same.
What happens to particles when heat is removed from them?
They slow down and get closer together
What happens to particles when they are heated?
They speed up and spread out
What would be the effect on the particles if more heat is supplied to the system?
They would speed up
How is energy transferred?
Through the collisions of the particles
12500000
Trailing zero at the end of a WHOLE NUMBER, which does not have a decimal are not significant
All phase changes (changing states) requires energy to be added or taken away. True or false?
True
In an exothermic phase transition, heat energy is transferred from the system to its surroundings. True or false?
True
The specific heat is the amount of energy needed to raise the temperature one degree Celsius of 1 gram of a substance. True or false?
True
12 eggs
Unlimited
What is it called when a liquid goes to a gas?
Vaporization
Vaporization
Vaporization at the surface of a liquid that is not boiling
Water has a specific heat of 4184 J/KgºC. Wood has a specific heat of 1760 J/KgºC. What material needs more energy to raise the temperature 1ºC
Water
Why is water a liquid at room temperature?
Water molecules have a strong attraction for each other (would have to heat it up more to separate the particles)
Can anything be proven?
nothing can be proved, all variable cannot be controlled, can't be done perfectly
Theories
occur after many experiments and explains why
Formula for solving specific heat problems
q = mcΔT
A high specific heat means...
It requires more energy to change temperature
What unit do you use to measure Thermal Energy?
J
What is the equation for kinetic energy?
KE = ½ mv squared
On this temperature scale, "zero" represents the temperature at which molecules have the lowest energy possible.
Kelvin
With which temperature scale is temperature directly proportional to average kinetic energy?
Kelvin
What does temperature measure?
Kinetic Energy
Which state of matter has particles that are somewhat close together and have enough kinetic energy to slide past each other?
Liquid
__________ have a definite volume and tend to take the shape of their container.
Liquids
For a skillet, used for cooking, do you want a high or low specific heat?
Low, so that it will change temperature quickly
Gas pressure is measured with a...
Manometer
The amount of matter in a substance, or object, is its __________.
Mass
Why does a liquid's rate of evaporation increase when the liquid is heated?
More molecules have enough energy to overcome the attractive forces holding them in the liquid.
Gas particles have the ________ kinetic energy because they move the fastest.
Most
The kinetic theory of matter states that all particles are constantly _____.
Moving
135
Non-Zero digits (1-9) are always significant
Chemical energy
Only if a new substance is formed (atoms reargued with atoms)
What is not true according to the kinetic theory?
Only particles of matter in the gaseous state are in constant motion.
What happens to particles at higher temperatures?
Particles in an object move faster
Which are the first particles to evaporate from a liquid?
Particles with the highest kinetic energy
E(ph) is what?
Phase energy
Addition/subtraction with sig figs
Position of sig figs
What is the symbol for Thermal Energy?
Q
What is thermal energy given off as when heat is given or taken away?
Q
What happens to vapor pressure when you add a solute to a solution?
It lowers the vapor pressure
What happens to vapor pressure when you add salt to water?
It lowers the vapor pressure.
Explain (in terms of the collisions of particles) why the change has the affect you predicted.
If the volume decreases, the gas particles don't have as far to collide with the walls of the container so there are more collisions with the walls. A higher temperature also increases the pressure because the faster moving particles will collide more often with the walls of the container. At constant P, increasing the temperature will cause an increase in volume, because the particles are moving faster and away from each other causing an expansion.
Why does the collision of the particles change with the predicted effects?
If you heat an object up, the particles bounce off of the sides faster.
Control group
In an experiment, the group that is not exposed to the treatment; contrasts with the experimental group and serves as a comparison for evaluating the effect of the treatment.
As the volume of a gas decreases, the pressure of the gas will _______ if the temperature remains the same.
Increase
How do you make the water molecules evaportate faster?
Increase the number at the surface and increase the number moving fast enough.
How do you increase the number of molecules at the surface?
Increase the surface and increase the temperature.
As temperature rises, what happens to an atom's kinetic energy?
Increases
As the temperature of an enclosed gas increases, the pressure _____.
Increases
At a constant temperature, the volume decreases. What happens to the pressure?
Increases
At a constant volume, the pressure increases. What happens to the temperature?
Increases
Water could be made to boil at 105C instead of 100C by
Increasing the external pressure
If a sealed syringe is plunged into cold water, in which direction will the syringe piston slide?
Inwards.
What happens to the average kinetic energy of the water if the fastest molecules leave?
It decreases.
What happens to the rate of evaporation of a liquid as the liquid is cooled?
It decreases.
What happens to the temperature of a liquid as it evaporates?
It decreases.
If energy is added to a boiling liquid, what happens to the temperature of the liquid?
It does not change.
If a liquid is sealed in a container and kept at constant temperature, how does its vapor pressure change over time?
It increases at first, then remains constant.
As the temperature of a liquid increases, what happens to its vapor pressure?
It increases.
What happens to a sample of a gas' thermal energy when it's heated?
It increases.
Why is salt added to roads & walkways in the winter?
It is added to lower the freezing point and prevent ice from forming.
In equilibrium between the liquid state and the gas state, what is true about the rate of evaporation?
It is equal to the rate of condensation.
The volume of a gas is doubled while the temperature is held constant. How does the pressure change?
It is reduced by one half.
What are the basic properties of the Kinetic Molecular Theory (KMT) as they relate to gases?
The particles of a gas: are in constant motion, move in straight lines until they collide with another particle or a wall of the container in which they are enclosed, experience elastic collisions (no energy transfer is loss, equal give and take relationship), they do not stick to other particles, the speed of the particles relates to their temperature, the pressure of a gas is related to the frequency and impact of the collisions of the gas particles with the sides of the container in which they are enclosed.
What is the definition of vapor pressure?
The pressure exerted by the vapor phase of a substance at equilibrium with its liquid phase for a given temperature.
Why does air escape from a tire when the tire valve is opened?
The pressure outside the tire is lower than the pressure inside of the tire.
The amount of heat transferred from an object depends on
The specific heat capacity, initial temperature, and the mass of the object
The strength of inter molecular forces varies between liquids, therefore they will have _____.
The strength of inter molecular forces varies between liquids, therefore they will have
Chemistry
The study of the composition of matter and the changes that matter undergoes
How does sweat cool you down?
The sweat evaporates by taking heat from your body and changing from a liquid to a gas
If the rate of boiling equals the rate of condensation...
The system is in equilibrium
Boiling point
The temperature at which a substance boils
Melting point
The temperature at which something melts
The average kinetic energy of the particles of a substance is directly proportional to what?
The temperature of the substance.
An increase in temperature of a contained liquid causes the vapor pressure to do what?
The vapor pressure above the liquid to increase.
What happens to the volume of a gas as its pressure approaches infinity?
The volume approaches zero.
What happens to the volume of a gas as its temperature approaches absolute zero?
The volume approaches zero.
Why is a gas easier to compress than a liquid or a solid?
The volume of a gas' particles is small compared to the overall volume of a gas.
When gaseous water condenses to liquid water, what happens to the energy?
The water releases energy to the surroundings.
What happens when you put a lid on a cup of water?
There is no condensation and it is evaporating, as more and more water vapor forms, more condensation appears.
What happens at absolute zero?
There is no movement, the particles stop.
E(th) is what?
Thermal energy
If two objects have reached the same temperature they have reached:
Thermal equilibrium
What is the relationship between pressure and temperature?
They are interchangeable. (If pressure increases, then temperature increases by an equal amount in order to keep the volume constant.)
What is the relationship between volume and temperature?
They are interchangeable. (If volume increases, then temperature increases by an equal amount in order to keep the pressure constant.)
What is the relationship between pressure and volume?
They are inverse. (If pressure increases, then volume decreases. If pressure doubles, then the volume halves).
Explain why one must use the absolute temperature scale to solve gas problems.
We use the absolute temperature scale because it reflects the physical reality at absolute zero; no pressure means no collisions with the walls of a container which means no movement. If there is no movement, there is no kinetic energy and since the temperature measures kinetic energy, the temperature is zero. Celsius temperatures are based on a convenient scale.
Depositing / Deposition
When a gas goes directly to a solid
Condensation
When a gas goes to a liquid
Boiling
When a liquid goes to a gas
Freezing
When a liquid goes to a solid
Subliming / Sublimation
When a solid goes directly to a gas
Melting
When a solid goes to a liquid
How does temperature effect particle motion?
When particles are heated up, they move faster.
Why can't there be anything colder than absolute zero?
You cannot have a negative movement.
Are you adding or removing heat when it goes from a solid to a liquid to a gas?
You're adding heat (Endothermic)
Are you adding or removing heat when it goes from a gas to a liquid to a solid?
You're removing heat (Exothermic)
0.0000005
Zeros at the beginning of a number are not significant
12500.
Zeros at the end of a number and after the decimal point are significant