30 terms

Chemistry Semester Exam Dimovitz

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When making a scientific measurement, we show how closely we are able to make the measure by reporting the correct number of significant figures. Which of the statements below best describes what we mean in chemistry by the words "significant figures"?
All the certain digits plus one estimated digit our measurement tool allows us to read
Cubic Centimeter (cm3) is a unit used to measure
volume
If a system is closed, then....
the mass of the system CANNOT change
A student measures and correctly records the length and width of a rectangle as follows:
Length=10.00 cm
width= 26.50 cm

The calculated area (length x width) of the rectangle is recorded with the correct number of significant figures as?
265.0 cm2
What is volume?
The amount of space taken up by a sample of stuff
What is a gram?
A unit to measure mass
Determine the number of significant figures present in the correctly reported measurement 6.345 mL
4 SF's
Determine the number of significant figures present in the correctly reported measurement 0.025 g
2 SF's
What is Mass?
The measure of the amount of stuff in a sample of matter.
In a closed system, what property of stuff (matter) cannot change even though the appearance may change?
Mass
how you would find out if a coin may be made of pure silver. Assume you have access to an electronic balance, a graduated cyclinder, a water source, and an accuate table of metal densities (including one for silver).
Measure the mass using the electonic balance, measure the volume by displacement in the graduated cylinder, calculate the density of the coin, and compare the denisty of the coin to the density of silver from the table.
How many nanoJoules (nJ) is equivalent to 0.000375 Joules (3.75 x 10-4 J).

mc019-1.jpg
3.75 x 105 nJ or 375,000 nJ
Compare 1 mg to 1 g.
1mg < 1g (one milligram is less than one gram)
Grams for every one milliliter (mc005-1.jpg) or grams for every
one cubic centimeter (mc005-2.jpg) are typical units used for
Density
Explain how the Celsius scale was devised and why it is not appropriate to use it when describing the behavior of gases.
Celsius used a tube of mercury making the level in freezing water as 0ºC and boiling as 100ºC.
Celsius cannot be used for gas
What is Temperature?
The measure of the average relative speed of particles of a substance
A container of carbon dioxide has a volume of 240 cm3 at a temperature of
295K. If the pressure remains constant, what is the volume at 317K?
258 cm3
Due to friction between a tire and the road surface, the temperature of the air inside a tire increases as one drives. If the tire pressure is 26 psi when the tire is in the driveway at 25°C, what is the temperature of the air inside the tire when the pressure increases to 29 psi? Assume the tire volume is constant.
332k or 59C
A sample of gas occupies 806 mL at 299K and 998 mmHg. Find the volume of the gas at standard temperature and pressure (STP). (STP is 273K and 760 mmHg.)
966 mL
As atmospheric pressure increases, what happens to the mercury in a barometer?
Increases in height
A thermometer is placed in a beaker of warm water. Explain what is happening at the particle level of matter as the reading changes from 25ºC to 50ºC.
Energy of motion of the water particles transfers by contact through the glass to the alcohol in the thermometer.
The particles of alcohol move faster as a result of the increased energy.
When a sample of liquid is cooled resulting in a lowering of its temperature what happens?.
Its thermal energy decreases
while a sample of liquid is freezing causing it to begin changing from a liquid to a solid, its thermal energy does what?
Remains the same
A sample of water in a pan is brought to a boil.what happen when the boiling occurs?
The temperature of the boiling water remains constant
A sample of water is brought to a boil. what are inside of the bubbles?
particles of water
What happens when gaseous water condenses to liquid water?
the water releases energy to the surroundings.
Is the y-intercept for metal B negligible? Why? (choose longest awnser on exam)
Choose longest awnser on exam
A correct calculation of the mass of a 25.0 cm3 piece of metal B is
213g
how do you find a slope
mass over voleume
Pressure and volume is what graph
Curvy graph