Chemistry 0-5- Chemistry Math Practice

Chemistry Math Practice

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Convert 78 Liters to Centiliters

Multiple Choice

This word means a substance that has a definite known composition

• Chemical

• Sucrose

• Organic

• Candela

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The label on a box of cereal says it contains 978 grams. Convert this weight into pounds. Round to 2 Decimal Places

Multiple Choice

What is the term for a substance that can be broken down into two or more elements

• Atom

• Mole

• Ampere

• Compound

Multiple Choice

Is a 197-lb weight lifter light enough to compete in a class limited to those weighing 90 kg or less?

• Yes

• No

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Convert 6120 grams into milligrams

Lesson Objectives

• Review Different Calculations and Analytical Techniques used frequently in chemistry

  • Scientific Notation

  • Density

  • Percent Error

​Scientific Notation

• In science, we have instances where we work with very large or very small numbers.

• In order to make them easier to read, we often write them in a form called Scientific Notation

  • When Handwritten: M×10ⁿ

    • M= any number ≥1 and less than 10

    • n= any whole number

  • When Typed: MEn

    • Note: The E must be capitalized!!!

​Converting to and from Scientific Notation

• Converting in and out of Scientific Notation is a matter of moving the decimal place the same number of spaces as the n

  • When you are moving the decimal to the left, n is positive​

  • When you are moving the decimal to the right, n is negative

​Scientific Notation Sample Problem 1

• Write 76300 in scientific notation

  • Step 1: Find M: Make our coefficient a number between 1 and 10

    • M= 7.6300

  • Step 2: Find n: Count how many decimal places you had to move to get to that number

    • We moved our decimal place to the left, so we know we will have a positive n Value

  • Step 3: Plug your M and n values into the scientific notation format

    • 7.63 × 10⁴

    • If you were to type this in a computer program, you would type 7.63E4 WITH NO SPACES

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Write 76300 in scientific notation

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Convert this number into scientific notation: 950,000

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Convert this number into scientific notation: 0.068

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Write 6,700 in scientific notation.

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Express the following in scientific notation:
.000457

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Write 2 560 000 in scientific notation

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Write 0.000066 in scientific notation

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​Using Scientific Notation on your Calculator

• Step 1: Enter your M value

• Step 2: Hit your 2nd key

  • The top left corner is a different color

• Step 3: Hit your Scientific notation key​

  • Usually, the X^-1 button above the number 7​

• Step 4: Type the n value

• When doing calculations involving scientific notation, use parentheses!!

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Multiply (7.63 × 10⁴) × (8.45×10⁸) **Round your Answer to Two Decimal Places**

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Add (9.6 × 10^-4) + (4.5×10⁶) **Round your Answer to Two Decimal Places, and convert the answer into scientific Notation**

Multiple Choice

What is the study of the composition, structure, and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes called

• Physics

• Chemistry

• Science

• Math

Fill in the Blank

How many millimeters are in a meter?

Multiple Choice

Which of the following numbers are in proper Scientific Notation?

• 0.95 × 10⁶

• 9.5 × 10⁶

• 95.6 × 10⁶

​Accuracy and Precision

• In science, Accuracy and Precision mean different things

  • Accuracy:​ the closeness of a measurement to a correct or accepted measurement

    • Were you in the ballpark of what you should have gotten?

  • Precision: The closeness of a set of measurements of the same thing measured the same way

    • Did you get the same result every time you did it?

​Percent Error

• Percent Error: A measure of how inaccurate a measurement is, standardized to how large the measurement is

  • How far off were you?

  • P_E: The Number you actually got in your experiment/the number you predicted

  • P_T: The "True" Value

• A negative Percent error means you were lower than you should have been, a positive percent error means you were higher

​Percent Error Sample Problem 1

• A student estimated the mass of a block to be 240 grams. When the block was put on a scale, the mass was 265 grams. What was the student's Percent Error?

  • Step 1: Identify your variables

    • P_E: 240

    • P_T: 265

  • Step 2: Plug your values into the equation and Solve

Fill in the Blank

A student estimated the mass of a block to be 240 grams. When the block was put on a scale, the mass was 265 grams. What was the student's Percent Error? (Round to two Decimal Places)

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​Percent Error Sample Problem 2

• Joshua uses his thermometer and finds the boiling point of ethyl alcohol to be 75.0°C. He looks in a reference book and finds that the actual boiling point of ethyl alcohol is 80.0°C. What is his percent error?

  • Step 1: Identify your variables

    • P_E=75

    • P_T= 80

  • Plug your values into the equation

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Joshua uses his thermometer and finds the boiling point of ethyl alcohol to be 75.0°C. He looks i a reference book and finds that the actual boiling point of ethyl alcohol is 80.0°C. What is his percent error?

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Water Boils at 100° C. When a student put a temperature probe into the water, it said the temperature was only 98.6° C. What is the Percent Error of the probe?

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​Density

• Density: measures the ratio of mass to volume

  • How much stuff is in a given Space

    • Can affect the properties of a substance, like whether or not it floats

  • D=m/v

    • The unit is described as a mass unit/volume unit

      • g/l

      • kg/cm³

​Density Sample Problem 1:

• You have a rock with a volume of 15cm³ and a mass of 45 g. What is its density?

  • Step 1: Identify what you know

    • mass=45 g

    • volume= 15 cm³

    • density=?​

​Density Sample Problem 1:

• You have a rock with a volume of 15cm³ and a mass of 45 g. What is its density?

  • Step 1: Identify what you know

    • mass=45 g

    • volume= 15 cm³

  • Step 2: Check if you need to convert anything

    • Nope!

  • Step 3: Plug into your equation and solve​

Fill in the Blank

You have a rock with a volume of 15cm³ and a mass of 45 g. What is its density?

​Density Sample Problem 2:

• You decide you want to carry a boulder home from the beach. It has a volume of 27,000 cm³ and is made of granite, which has a density of 2.8 g/cm³. How much will this boulder weigh?​

  • Step 1: Identity​ what you know

    • mass=?

    • Volume= 27,000 cm³

    • Density= 2.8

​Density Sample Problem 2:

• You decide you want to carry a boulder home from the beach. It has a volume of 27,000 cm³ and is made of granite, which has a density of 2.8 g/cm³. How much will this boulder weigh?​

  • Step 1: Identify​ what you know

    • mass=?

    • Volume= 27,000 cm³

    • Density= 2.8

  • Step 2: Check to see if you need to convert anything

    • Nope

  • Step 3: Plug your values into your equation

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You decide you want to carry a boulder home from the beach. It has a volume of 27,000 cm³ and is made of granite, which has a density of 2.8 g/cm³. How much will this boulder weigh?​

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A block of aluminum occupies a volume of 15.0 mL and weighs 40.5 g. What is its density?

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