Vinegar is typically 5-8% acetic acid. It contains water and acetic acid and has uniform composition. So, vinegar is a homogeneous mixture.
Graphite is composed of only carbon atoms. So, graphite is an element
Water molecules are composed of hydrogen and oxygen atoms. So, water (H2O) is a compound.
Tungsten (W) is an element, made of only one kind of atoms. Note that Tungsten appears on the periodic table of elements.
Bromine molecules (Br2) are composed of only bromine atoms. So, bromine is an element. Note that Bromine appears on the periodic table of elements.
Which of the following is NOT matched correctly?
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Iodine (I2) molecules are composed of only Iodine atoms. So, Iodine is an element. Note that Iodine appears on the periodic table of elements.
Chicken noodle soup contains more than one substance which makes it mixture. Since, the composition is not uniform throughout, it is a heterogeneous mixture.
Aluminum carbide is a single substance. It is composed of more than one kind of atoms (aluminum and carbon). It is a compound.
A rock is a mixture because it contains more than one substance--several minerals and organic matter. The composition is not uniform throughout. Hence, it is a heterogeneous mixture.
Gold (Au) is an element, made of only one kind of atoms. Note that Gold appears on the periodic table of elements.
Which of the following is NOT an extensive property?
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Density is mass per unit volume. No matter how much substance you have, mass per milliliter will be a constant for the substance. Since density is independent of amount of substance, it is an intensive property. Note that ratio of two extensive properties will be intensive.
Mass depends on amount of substance, so, it is an extensive property.. A larger quantity will weigh more.
Volume depends on amount of substance, so, it is an extensive property. A larger quantity will occupy more space.
Length depends on amount of substance, so it is an extensive property. Example, larger amount of rope will have greater length.
Energy depends on amount of substance, so it is an extensive property. Example, a larger quantity of food contains greater energy.
Which of the following is a chemical change?
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Sublimation is the process of a substance changing it's state from solid to gas, without passing through the liquid state. The distance between the molecules increases greatly during this change of state. However, no new substances are formed, so, sublimation is a physical change.
When an apple turns brown, say by exposing it to air, a chemical reaction called oxidation occurs due to the reaction of oxygen with the chemical substances (polyphenols) in the apple's flesh. New substances are formed in the process, so, it is a chemical change.
The chemical reaction can be simplified to: Polyphenol Oxidase + O2 &arr; Melanin (Brown Color)
When a substance is magnetized, it atoms align in the direction of the magnetic field. No new substances are formed in the process, so, it is a physical change.
Sand and water do not react. Mixing them does not generate new substances, so, it is a physical change.
When a substance boil's, it changes from liquid state to gaseous state. The distance betwen the water molecules increases greatly when water changes from liquid to gaseous state. However, no new substance is created in the process, so, boiling is a physical process.
Which of the following is a NOT a chemical change?
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Rusting is a chemical process because iron, oxygen and water react together to create new substance (hydrated form of ferric oxide) commonly known as rust.
During digestion, food is broken down into smaller molecules. The process involves formation of new substances, so, it is a chemical process.
Iron and hydrochloric acid react together to form new substances (iron chloride and hydrogen gas). Since new substances are formed in the process, it is a chemical change.
Steam is water in vapor state. The identity (ie. chemical composition) of water does not change during condensation; it just changes state from gas to liquid, and no new substances are formed. Therefore, it is a physical process.
During combustion of a fuel, the fuel reacts with oxygen to produce other gaseous substances such as carbondioxide and water vapor. Since new substances are formed, combustion is a chemical change.
How many significant digits are in the following quantity? 0.0050 cm
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All zeroes in a measurement may not be significant. Review how to count significant digits here.
Some of the decimal zeroes in this example are leading zeroes. Review how to count significant digits here.
Which of the following quantities has 4 significant digits?
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This number has 2 significant digits. Review how to count significant digits here.
There are two leading zeroes, one non-zero digit and three trailing zeroes in this number that has a decimal point. Review Topic.
This number has 2 significant digits. Review how to count significant digits here.
This number has 3 significant digits. The 105 merely indicates the location of the decimal point.
This number has 3 significant digits. Review how to count significant digits here.
How many significant digits should be in the result to the following calculation? 99.350 cm + 8.4 cm
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When adding or subtracting numbers, round the result to the same number of digits as the number with the least number of decimal places, not signficant digits.
How many decimal places will be in the result? How many significant digits?
When adding or subtracting numbers, round the result to the same number of digits as the number with the least number of decimal places, not signficant digits.
When adding or subtracting numbers, round the result to the same number of digits as the number with the least number of decimal places.
How many decimal places will be in the result? How many significant digits?
The result should be rounded to one decimal place, which will amount to four significant digits.
When adding or subtracting numbers, round the result to the same number of digits as the number with the least number of decimal places.
What is answer to the following calculation after it is rounded to the appropriate number of significant digits?
12 cm x 9.80 cm
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When multiplying or dividing numbers, round the result to the same number of digits as the number with the least number of significant figures.
The result is rounded up to 2 significant digits and zero is used a placeholder in this case.
When multiplying or dividing numbers, round the result to the same number of digits as the number with the least number of significant figures.
There are correct number of significant digits in the answer, but it has not been rounded correctly. Review Significant Figures in Calculations.
12 x 9.800 cannot be just 12! You must use a placeholder.
How many significant digits should be in the answer to the following calculation?
(0.973 x 35.44) - 0.43
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Here is a video solution to a similar problem (not the same problem): video
Paranthesis should be evaluated first, followed by subtraction.
Here is a video solution to a similar problem (not the same problem): video
Parenthesis is evaluated first:
For multiplication:
0.973 (3 sig figs)
x 35.44 (4 sig figs)
= 34.48312 (round to 3 sig figs).
Three significant digits in 34.48312 is equivalent to 1 decimal place.
Next, we evaluate the subtraction
For substraction:
34.48312(rounded to 1 decimal)
- 0.43 (2 decimals)
= 34.05312 (round to 1 decimal) = 34.1
The result, therefore, has three significant digits.
Here is a video solution to a similar problem (not the same problem): video
Paranthesis should be evaluated first, followed by subtraction.
Here is a video solution to a similar problem (not the same problem): video
Here is a video solution to a similar problem (not the same problem): video.
What are the two ways to express the conversion factor between decimeter (dm) and meter (m)?
The prefix, deci means one-tenth. A decimeter is tenth of a meter (1 dm = 0.1 m); or, a meter has ten decimeters (1 m = 10 dm)
Note: In scientific notation, negative exponent beside larger unit or positive exponent beside smaller unit.
Gram is a larger unit than a microgram. Review metric prefixes here.
Conversion factor: 1 µg = 10-9 g or, 1g = 109 µg
Gram is larger than a microgram. So, grams contain lots of micrograms. The answer should be a big number, ie. positive exponent in the scientific notation.
Gram is a larger unit than a microgram. Review metric prefixes.
Millimeter is larger than nanometers. There should be lots of nanometers in a the given amount of millimeters; but, the value you chose is very small! Review metric prefixes here.
The mirrors in the Weber telescope are coated with gold to increase the reflectivity of the telescope in infrared light.
The thickness of the gold coating is 100 nm. What is the thickness in centimeters?(g)
You may have squared the given number as well. Only conversion factor must be squared. Review topic here.
in2 is larger than cm2. When converting to a larger unit, you should end up with a smaller number than what is given. Review topic here.
The pressure of a gas is 35.6 lb/in2. What is the pressure in kg/m2. (g)
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Possible error in metric conversion factors.
Check calculation. You may have not used paranthesis in the calculator.
It is possible you treated m2 as if it is in the numerator during dimensional analysis.
Write kg over m2 with a horizontal bar so you see which unit is in the numerator and which one in the denominator clearly.
The capacity of a gas tank in an automobile is 13.2 gal. What is the volume in m3? 1 gal = 3.785 L
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Possible error while converting Liters to m3; convert via dm3 or cm3. Review topic here.
gal → L → dm3 → m3. Conversion factors: 1 L = 1 dm3, 103 dm3 = 1 m3 (Note that the conversion factor between m and dm is cubed). You may also convert gal → L → mL → cm3 → m3
Convert gal → L → dm3 → m3. Review conversion factors for volume here.
Convert gal → L → dm3 → m3. Review conversion factors for volume here.
Convert gal → L → dm3 → m3. Review conversion factors for volume here.
A cube has a side of 1.6 inches. What is the volume of the cube in Liters?
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Review conversion factors for units of volume here.
Volume of a cube = (length)3. Review conversion factors for units of volume here.
Volume = (length)3 = (4.0 cm)3 = 64 cm3 Convert cm3 → mL → L
Volume of a cube = (length)3. Review conversion factors for units of volume here.
Volume of a cube = (length)3. Review conversion factors for units of volume here.
The density of a substance is 8.96× 10-3 g/mm3. What is it’s density in kg/L?
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Perform dimensional analysis converting one unit at a time, taking note whether the unit to be converted is in the numerator or denominator. g/mm3 → kg/mm3 → kg/dm3 → kg/L (Note: you may convert mm3 to dm3 via the base unit, m3 (ie. mm3 → m3 → dm3. Remember to cube the conversion factors for length to obtain conversion factors for volume)
Hint: mm3 should be converted to L via either cm3 or dm3. Review conversion factors for units of volume here.
Hint: mm3 should be converted to L via either cm3 or dm3. Review conversion factors for units of volume here.
Hint: mm3 should be converted to L via either cm3 or dm3. Review conversion factors for units of volume here.
Hint: mm3 should be converted to L via either cm3 or dm3. Review conversion factors for units of volume here.
An airplane averaged 450 miles per hour on a trip. What was it’s speed in feet per second? (1 mi = 1.609 km 12 in = 1 ft 1 in = 2.54 cm)
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Perform dimensional analysis converting units in the numerator and denominator, one at a time. mi/hr → km/hr → m/hr → cm/hr → in/hr → ft/hr → ft/min → ft/s
Perform dimensional analysis converting units in the numerator and denominator, one at a time. Review Topic.
Perform dimensional analysis converting units in the numerator and denominator, one at a time. Review Topic.
Perform dimensional analysis converting units in the numerator and denominator, one at a time. Review Topic.
Perform dimensional analysis converting units in the numerator and denominator, one at a time. Review Topic.
You are buying carpet to cover a room that measures 38 ft by 40 ft. The carpet costs $18 per square yard. How much will the carpet cost? 1 yd = 3 ft
Area = length × width = 38 ft × 40 ft = 1520 ft2. Use dimensional analysis to go from ft2 to $. Review conversion factors for areas and volume ft2 → yd2 → $  Conversion factors: 1 yd2 = 9 ft2; 1 yd2 = 18$
Area = length × width = 38 ft × 40 ft = 1520 ft2
An average human heart beats 60 times per minute. If the average person lives to the age of 86, how many times does the heart beat in a lifetime?
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hHint: Given unit: 86 yr Desired unit: beats Conversion factor from the problem statement: 60 beats = 1 min;
86 yr → day → hr → min → beats. Conversion factors: 60 beats = 1 min; 1 year = 365 days; 1 day = 24 hr; 1 hr = 60 min
Hint: Given unit: 86 yr Desired unit: beats Conversion factor from the problem statement: 60 beats = 1 min
Hint: Given unit: 86 yr Desired unit: beats
Conversion factor from the problem statement: 60 beats = 1 min;
Hint: Given unit: 86 yr Desired unit: beats.
Conversion factor from the problem statement: 60 beats = 1 min;
A smelting company uses steel ingots, each weighing 500 lb, to manufacture ball bearings. Three ingots can be melted to produce 450 ball bearings. How many metric tons of ingots are needed to produce a million ball bearings? 1 kg = 2.2 lb 1000 kg = 1 metric ton
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Hint:Given unit: 106 ball bearings Desired unit: tons Other conversion factors are stated in the problem.
Hint:
Given unit: 106 ball bearings Desired unit: tons
Other conversion factors are stated in the problem.
Hint:Given unit: 106 ball bearings Desired unit: tons
Other conversion factors are stated in the problem
Hint:
Given unit: 106 ball bearings Desired unit: tons
Other conversion factors are stated in the problem
6 ball bearings → ingots → lb → kg → ton
Other conversion factors: 3 ingots = 450 ball bearings; 1 ingot = 500 lb
Gasoline has a fuel value of 48 kilojoules per gram. How much energy in joules can be obtained by filling an automobile’s 16.3-gallon tank with gasoline, assuming gasoline has a density of 0.70 kg/dm3? 1 gal = 3.785 L
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16.3 gal → L → dm3 → kg → g → kilojoules → joules
Hint:
Given unit: 16.3 gal Desired unit: Joules
Hint:
Given unit: 16.3 gal Desired unit: Joules
Hint:
Given unit: 16.3 gal Desired unit: Joules
Hint:
Given unit: 16.3 gal Desired unit: Joules
A manometer is a device used to measure pressure. A 50.00 pound flask of mercury costs $132.50. The density of mercury is 383.24 kg/ft 3. It takes 4.950 in 3 of mercury to make 2 manometers. Find the price of the mercury used to make 25 manometers.
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25 manometers (or devices) → in3 → ft3 → kg → lb → $ To convert in3 → ft3, cube the conversion factor between inches and feet (that is, 123 in3 = 1 ft3)
Hint Given: 25 manometers or 25 devices Desired unit: $
Conversion factors from the problem: 2 manometers = 4.950 in3
1 ft3 = 383.24 kg
50.00 lb = $132.50
Hint Given: 25 manometers or 25 devices Desired unit: $
Conversion factors from the problem: 2 manometers = 4.950 in3
1 ft3 = 383.24 kg
50.00 lb = $132.50
Hint Given: 25 manometers or 25 devices Desired unit: $
Conversion factors from the problem: 2 manometers = 4.950 in3
1 ft3 = 383.24 kg
50.00 lb = $132.50
Hint Given: 25 manometers or 25 devices Desired unit: $
Conversion factors from the problem: 2 manometers = 4.950 in3
1 ft3 = 383.24 kg
50.00 lb = $132.50
Perhaps you made a mistake in converting in3 to ft3