Chapter 3: Measurements and Calculations Flashcards
What are the three common scales used when measuring temperature in chemistry?
Celsius
Kelvin
Fahrenheit
What does the temperature scale Kelvin represent?
The Absolute Scale
What is the formula to convert Kelvin to Celsius?
°C = K - 273
^ if this is not in your calculator, add it now.
What formula is used to convert Celsius to Fahrenheit?
°F = 9/5°C + 32
^ if this is not in your calculator, add it now.
What formula is used to convert Fahrenheit to Celsius?
°C = 5/9(°F - 32)
^ if this is not in your calculator, add it now.
Define significant figures and their rules:
each of the digits of a number that are used to express it to the required degree of accuracy, starting from the first NONZERO digit.
examples:
6.658 has four significant figures
129 has 3 significant figures
5,007 has four significant figures
Trailing zeros in a number are only significant if the number contains a decimal point.
examples:
100.4 has 4 significant figures
100 has 1 significant figure
Zeros in the beginning of a number whose only function is to place the decimal point are not significant.
example:
0.0025 has 2 significant figures
Zeros following a decimal significant figure ARE significant.
examples:
0.000470 has 3 significant figures
0.47000 has 5 significant figures
Determine the number of significant figures:
5.432g
4
Determine the number of significant figures:
2873.0cm
5
Determine the number of significant figures:
2500.0cm
5
True or False:
When multiplying and dividing, limit and round to the least number of significant figures in any of the factors.
True.
Example:
23.0cm x 432cm x 19cm = 188,784cm^3
The answer is expressed as 190,000cm^3 since 19 cm in the problem has only two significant figures.
True or False:
When adding and subtracting, limit and round your answer to the least number of whole numbers that make up your answer.
False.
When adding and subtracting, limit and round your answer to the least number of DECIMAL PLACES in ANY of the numbers that make up your answer.
Example:
123.25mL + 46.0mL + 86.257mL = 255.507mL
The answer is expressed as 255.5mL since 46.0mL in the problem only has one decimal place.
Add & express in sig fig:
12cm + 0.031cm + 7.969cm =
20cm
Add & express in sig fig:
63.489cm + 126.2cm + 68.85cm + 12.05cm =
270.6 cm
Multiply & express in sig fig:
5.0cm x 5cm =
20 cm^2
Multiply & Express in sig fig:
4.218cm x 6.5cm =
27cm^2
What type of units is mass measured?
Kilograms (kg)
What type of units is length measured?
meters (m)
What type of units is used to measure time?
seconds (s)
What type of units is used to measure temperature?
kelvin (K)
Do you have this cheat sheet in your calculator?
if not, add it now :)
Review your density (rainbow) lab
I don’t have much to give you on density – so look over the lab
Express 1,870,000 in scientific notation.
1.87 x 10^6
The number 0.00003007 expressed in exponential notion is:
3.007 x 10^-5
The SI prefix that corresponds to a factor of 10^-3 is:
milli
The number of milliliters in 0.067 liter is:
36.7 mL
Consider the numbers 23.68 and 4.12
The sum of these numbers has significant figures, and the product of these numbers has significant figures. what are they?
4 and 3
Which of the following statements is true?
A. A change of 1°C is larger than a change of 1°F, but smaller than a change of 1 K.
B. A change of 1°F is larger than a change of 1°C, but smaller than a change of 1 K.
C. A change of 1°C is larger than a change of 1°F, and equal to a change of 1 K.
D. A change of 1°F is larger than a change of 1°C, and equal to a change of 1 K.
A change of 1°C is larger than a change of 1°F, and equal to a change of 1 K.
A 15.0-mL sample of a liquid has a mass of 12.3 g. What is the density of the liquid?
0.820 g/mL
The beakers shown in the image have different precisions as shown.
A. Report the volume of water beaker 1 with the proper number of significant figures.
B. Label the digits in each measurement from part A as “certain” or “uncertain.”
C. You pour the water from these three beakers into one container. What is the volume of liquid in the container reported to the correct number of significant figures?
A –
beaker 1: 26.4mL
B –
2 & 6 are certain, 4 is uncertain
C –
81 mL
