Parentheses ( ) Math Review. The Order of Operations tells us how to do a math problem with more than one operation, in the correct order.

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1 Problem Solving in Chemistry Math Review We are faced with problems each day, and not just in chemistry A solution (answer) needs to be found Trial and Error may work sometimes but, there is a method to problem solving that works better, and these are skills that no one is born knowing they need to be learned. The Order of Operations tells us how to do a math problem with more than one operation, in the correct order. P E M D A S Please Ecuse My Dear Aunt Sally Parentheses ( ) Eponents Multiply Divide Add + Subtract - This will help you to remember the order of operations. Please Ecuse My Dear Aunt Sally Please Ecuse My Dear Aunt Sally Parentheses ( ) Always do parentheses st. Eponents Always do Eponents nd.

2 Please Ecuse My Dear Aunt Sally Please Ecuse My Dear Aunt Sally Multiply Add + Divide Do multiplication and division rd, from left to right. Subtract - Do addition and subtraction th, from left to right. PEMDAS + - (9+) PEMDAS (9+) + ()+ ()+ + 9 To solve two-step equations, undo the operations by working backwards. Eample: Recall the order of operations as you answer these Ask yourself, questions.. What is the first thing we are doing to? Dividing by. What is the second Subtracting thing? To undo these steps, do the opposite operations in opposite order.. Add to both sides. Simplify. Divide both sides by. Simplify. Check your answer Solve - = = - = - (-) - = - - = -

3 . Add to both sides. Simplify. Clear the fraction -Multiply both sides by. Simplify. Check your answer Solve + + = =. y =. y = -. y =. y = E. Solve y =. z = -. z = -. z =. z = E. Solve z + = How to change percentages, into fractions and decimals A percentage is a special fraction. The % says, per hundred. For eample, %, is simply another way of writing the fraction / So, to change a percentage into a decimal, you always divide by For eample, % as a fraction is / so to change this into a decimal, you divide by %. To change decimal into a percentage Decimal Percentage To change a decimal into a percentage, you X by. X %

4 Finding Percentages of Different Numbers Problem: In a survey of pupils it was found that % had ipods. How many pupils had ipods? Change the percentage to a decimal, then multiply by the number of children. % =.. times = Scientific Notation A number is epressed in scientific notation when it is in the form a n where a is a whole number between and and n is an integer 9 Changing a Large Number Into Scientific Notation,, Where is the decimal point now? After the last zero. Where would you put the decimal to make this number be between and? Between the and the.,,. How many decimal places did you move the decimal? When the original number is more than, the eponent is positive. The answer in scientific notation is. Changing a Small Number Into Scientific Notation E..9 Where would the decimal go to make the number be between and? 9. The decimal was moved how many places? When the original number is less than, the eponent is negative Write.9 in scientific notation. a..9 - b..9 - c..9 d..9

5 Epress. - in decimal notation.. Epress. in decimal notation.,, On the graphing calculator, scientific notation is done with the button.. is typed. Use a calculator to evaluate: Type You must include parentheses if you don t use those buttons!! (. -) (. -). Write in scientific notation.. - Use a calculator to evaluate:. -9. On the calculator, the answer is:.e - The answer in scientific notation is - The answer in decimal notation is. Use a calculator to evaluate (.)(,). On the calculator, the answer is. The answer in decimal notation is The answer in scientific notation is. Use a calculator to evaluate (,,,)(). On the calculator, the answer is:. E + The answer in scientific notation is. The answer in decimal notation is Write (. )(. - ) in scientific notation. a.. - b.. - c.. d.. 9,,,

6 Share Price ($) (dependent variable) Volume (L) Volume (L) Bar Graph shows how many of something are in each category Chemistry Grades % % Pie Graph shows how a whole is broken into parts % % Percentage of Weekly Income Entertainment (%) Food (%) Clothing (%) Savings (%) A B C D F Line Graph shows continuous change Stock Price over Time Jan Feb Mar Apr Month Elements of a good line graph aes labeled, with units use the available space title neat 9 Temp. v. Vol. for a Gas at Constant Pressure Temp. (K) How to read a graph Interpolate - read between data points What volume would the gas occupy at a temperature of K? L Etrapolate - read data beyond data points What volume would the gas occupy at a temperature of K? ~ L 9 Temp. v. Vol. for a Gas at Constant Pressure Temp. (K) (independent variable)