Question 1 Rules for significant figures. All non zero numbers are Significant All zeros in between non zero numbers are significant All LEADING zeros are insignificant All TRAILING zeros are significant IF there is a decimal point

Question 2 When performing multiplication and division, one must round according to the least amount of SIGNIFICANT FIGURES. When performing addition and subtraction, one must round according to the least amount of DECIMAL PLACES.

Question 3 ACCURACY is the degree of closeness of measurements of a quantity to that quantity’s actual (true) value. PRECISION is the degree to which repeated measurements under unchanged condition show the same results.

Question 4 In order to make accurate measurements you have to round one decimal place past what is indicated on your tool of measurement. So for this example, the ruler is marked every 0.1 cm. The green rectangle looks like it is between 15.3 and 15.4. So any number between that is a reasonable guess (ie. 15.31, 15.32, 15.33, 15.34, 15.35, 15.36, 15.37, 15.38, 15.39)

Question 5 In order to make accurate measurements you have to round one decimal place past what is indicated on your tool of measurement. So our measuring device is marked every 10 unit of volume. Our liquid is somewhere between the 40 and 50 mark, closer to 50, more than 45. So anything in between 45 and 50 would be acceptable.

Question 6 In order to make accurate measurements you have to round one decimal place past what is indicated on your tool of measurement. So our measuring device is marked every 1 unit of volume. With a graduated cylinder we have to take the measurement at the bottom of the curve, or meniscus. Our liquid is somewhere between the 36 and 37 mark about halfway, so we should say 36.5.

Question 7 Solve: 1.23 m x 0.89 m = 1.0947 m^2 Solve: 123,000 m x 3,234 m = 397,782,000 m^2 123,000 has 3 significant figures, 3,234 has 4 so our final value must have 3 398,000,000 m^2 We round the 7 up based on the next decimal place over, which is 7. Solve: 1.23 m x 0.89 m = 1.0947 m^2 1.23 has three significant figures, 0.89 has two significant figures (leading 0’s are insignificant) 1.1 m^2 We round the 0 up based on the next decimal place over which is 9.

Question 8 How many significant figures are in the measurement 102.400 meters? All numbers are significant, the zero’s at the end (trailing) are significant because there is a decimal place. So there are 6 significant figures.

Question 9 Solve: 345.009 g – 23.009 g 345.009 23.009 322.000 Since both numbers share the same last decimal place, we have to round our reported value to the third decimal place.

Question 10 How many significant figures are in the measurement 0.00130 cm? 0.00130 has three leading zeros, which are insignificant The trailing zero is significant because there is a decimal place. Therefore, there are 3 significant figures.

Question 11 When performing the calculation 34.530 g + 12.1 g + 1,222.34 g, the final answer must have Only one decimal place. 12.1 g has the least amount of decimals places so one must round the final value to one decimal place.

Question 12 Convert the following measurement to scientific notation: 101 000 grams 1.01 x 105 g (standard) Or additionally 101 x 103 g

Question 13 Mass = 24.595 g Volume = 5.34 cm3 𝑑𝑒𝑛𝑠𝑖𝑡𝑦= 𝑚𝑎𝑠𝑠 𝑣𝑜𝑙𝑢𝑚𝑒 𝑑𝑒𝑛𝑠𝑖𝑡𝑦= 𝑚𝑎𝑠𝑠 𝑣𝑜𝑙𝑢𝑚𝑒 𝑑𝑒𝑛𝑠𝑖𝑡𝑦= 24.595 𝑔 5.34 𝑐𝑚 3 Density = 4.605805… 𝑔 𝑐𝑚 3 Least amount of sig figs is 3 Therefore 4.61 𝑔 𝑐𝑚 3

Question 14 Solve: 7.987 m - 0.54 m = ? 7.987 m - 0.54 m 7.447 m 0.54 has the fewest amount of decimal places so we need to round to it’s last decimal place, the 2nd decimal place. 7.45 m

Question 15

Question 16 Round the following measurement to three significant figures: 0.90985 cm2 The first zero is insignificant because it is leading, but every number after the first 9 is. Therefore to round to three significant figures one would round up to 0.910 cm2 The trailing zero would be significant because there is a decimal place.

Question 17 A CHEMICAL PROPERTY is a property of a substance that pertains to a chemical change involved with that substance. A PHYSICAL PROPERTY is a property that does not pertain to chemical changes and remain constant for any given substance.

Question 18 Refer to the previous question as a reference. _physical_______ a. boiling point _physical_______ b. density _chemical______ c. reactivity _physical ___ d. color (both acceptable) _physical ______ e. shape _physical ______ f. melting point/freezing point _physical______ g. solubility _chemical_____ h. flammability

Chemical or Physical Change Question 19 Step Chemical or Physical Change Sign  Mixing the various ingredients    Physical  each substance is mixed together, but does not change identity – ex. Salt doesn’t lose it’s saltiness etc.  Bake in the oven  Chemical The change in shape and consistency (fluffiness) is due to the production of a gas (carbon dioxide) which is the sign of a chemical reaction.

Question 20 Percent error = 𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 𝑉𝑎𝑙𝑢𝑒 −𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑉𝑎𝑙𝑢𝑒 𝑇ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 𝑉𝑎𝑙𝑢𝑒 x 100 2.1 𝑔 𝑚𝑙 − 2.3 𝑔 𝑚𝑙 2.3 𝑔 𝑚𝑙 x 100 Think of the measured value as the value you come up with, think of theoretical value as the value that is given to you. = −0.086 x 100 = 0.086 x 100 = 8.6 % Mass = 26 g Volume = 12.6 ml 𝑑𝑒𝑛𝑠𝑖𝑡𝑦= 𝑚𝑎𝑠𝑠 𝑣𝑜𝑙𝑢𝑚𝑒 𝑑𝑒𝑛𝑠𝑖𝑡𝑦= 26 𝑔 12.6 𝑚𝑙 Density = 2.06349..… 𝑔 𝑚𝑙 Least amount of sig figs is 2 Therefore 2.1 𝑔 𝑚𝑙 You can tell double check your calculation based on the behavior of the object. If it sinks to the bottom, you know that its density is more than that of water, thus its density has to be more than 1.