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AP Chemistry Chapter I Lesson 3 Significant Numbers.

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Presentation on theme: "AP Chemistry Chapter I Lesson 3 Significant Numbers."— Presentation transcript:

1 AP Chemistry Chapter I Lesson 3 Significant Numbers

2 Giving the Cat Bath

3 Question A sample of carbon dioxide that undergoes a transformation from solid to liquid to gas would undergo A sample of carbon dioxide that undergoes a transformation from solid to liquid to gas would undergo (A) a change in mass (B) a change in density (C) a change in composition (D) no change in physical properties (A) a change in mass (B) a change in density (C) a change in composition (D) no change in physical properties Answer B

4 Question A solution is a(n) A solution is a(n) (A) compound (B) pure substance (C) homogeneous mixture of substances (D) heterogeneous mixture of substances (A) compound (B) pure substance (C) homogeneous mixture of substances (D) heterogeneous mixture of substances Answer C

5 Chemical Equation Symbolic representation of the change or changes occurring. Symbolic representation of the change or changes occurring. sodium bicarbonate + hydrochloric acid Sodium chloride + water + carbon dioxide

6 Reactant Substances reacting to produce product. Substances reacting to produce product.

7 Product Substances that are produced. Substances that are produced. iron + oxygen Iron III oxide

8 Example 2 Na + Cl 2 2 NaCl 2 Na + Cl 2 2 NaCl Reactants Product Reactants Product

9 Accuracy How close is measurement to the true value. How close is measurement to the true value.

10 Precision Agreement between several measurements of some quantity. Agreement between several measurements of some quantity.

11 Ions electrically charged atoms or groups of atoms. electrically charged atoms or groups of atoms. Cations (+) Cations (+) charged ions charged ions Anion (-) charged ions Anion (-) charged ions

12 Convert 7 in to cm 7 in to cm 17.8 cm

13 Convert 179 m to cm 179 m to cm x 104 cm x 104 cm

14 Convert 15 km/L to mi/gal 15 km/L to mi/gal 35 mi /gal

15 Calculation of significant figures Preceding zeros do NOT count. Preceding zeros do NOT count. Ex: is 2 sig #s Ex: is 2 sig #s Zero between non zero digits count. Zero between non zero digits count. Ex: is 6 sig #s Ex: is 6 sig #s

16 Calculation of significant figures cont. Trailing zeros do NOT count. Trailing zeros do NOT count. Ex: 100 is 1 sig # Ex: 100 is 1 sig # Zeros behind the decimal after a non zero digit DO count. Zeros behind the decimal after a non zero digit DO count. Ex: 1.00 x 10 2 is 3 sig #s Ex: 1.00 x 10 2 is 3 sig #s

17 Answer Significant # for Significant # for A A B B sig #

18 Answer Significant # for: Significant # for: A A B B sig # 1 sig #

19 Rules for Significant figures in multiplying and dividing. Ex: 4.56 x 1.4 = 6.38 round to 6.4 use the number that has the least number of significant figures. Ex: 4.56 x 1.4 = 6.38 round to 6.4 use the number that has the least number of significant figures. Due to the least precise number. Due to the least precise number.

20 Rule for significant figures and addition and subtraction. Ex: round to nearest tenth due to digit with least precise measurement. Ex: round to nearest tenth due to digit with least precise measurement. So correct answer would be 31.1 due to (18.0). So correct answer would be 31.1 due to (18.0).

21 Mass Amount of matter in an object. Amount of matter in an object.

22 Volume 1 L = 1000ml = 1000 cm 3 = 1 dm 3 1 L = 1000ml = 1000 cm 3 = 1 dm 3

23 Temperature property of matter that determines whether heat energy can be transferred from one body to another and the direction of that transfer. property of matter that determines whether heat energy can be transferred from one body to another and the direction of that transfer.

24 Formulas: a. Convert o F to o C ( o F - 32) x 5/9 = o C b. Convert o C to o F o C x 9/ = o F Fahrenheit Celsius

25 Formulas: c. Convert o C to K o C = K or K = o C Lord Kelvin

26 Absolute Zero lowest possible temperature. Where all motion of molecules ceases. lowest possible temperature. Where all motion of molecules ceases.


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