University:
Campbell University
Course:
CHEM 111 | General Chemistry I
Academic year:

2020
Views:

450

Pages:

3
Author:

Hundebuchesn

jO unit ii INTRODUCTION TO CHEMISTRY m Name For each of the following problems use dimensional analysis (factor - label) to write equations. Show all units but do not calculate a final answer. 1. a) How many “loonies” have the same value as 650 dimes? /bO iie*, / / /gjnie - 6 0 d?/ m n $ ^ /0 _ d i / AcS b) Copper has a mass of 63.5 grams for every mole of atoms. What would the mass of 5.62 moles be? - £/j.r dq — 5. 6 2 mobs x (j ) -- JV T : c) How many minutes are there in 24 weeks? Ui — Q t)\ t /m' . f- 7 dccyf / h- & kc ( jetxr 2 ’ ? X i X 7 -A \ d) How long must an electrical current of 9.6 C per second flow in order to deliver 42.7 C? idrt ($ ) ' = t dO. l d x s &C e) The energy in food is often described in units called calories where one calorie is equivalent to 4.184 kJ. Bread has about 11 kJ of energy per gram. How calories of food energy would there be in 25 g of bread? (jC . /tiXas ) l X * k-1 // / 3 / C X X> i V J . Give one example of a derived quantity and give also the derived unit for this quantity, unit: quantity: . 5 Scientists often use what they call “significant digits” as they record data or do calculations. For example, when the value for a mass is recorded as 2.043 g, information about the uncertainty of this value is implied. Explain. ru . 6 o D fL/l /0.4 / - / erfxJy f n )< ' ? /5 / 6{ ft CJh- ts\ In what way is writing the uncertainty separately an advantage over using significant digits? range / 7. Round off the following measurements and write them without showing the uncertainty separately: a) 0.234 c) 9.99 8. ± ± 0.02 g 0.3 kg . 3 0 S3 /0.0 i O ^ . o 10. a) Describe the rule that should be applied when doing either an addition or a subtraction while using significant digits. _ Coitc nuv 5 -4- ev b) Describe the rule that should be applied when doing either a multiplication or a division while using significant digits. 3 11. The following calculations were done with a calculator . Round off the answers according to the rules of significant digits. f i f a) 0.345 + 1.23 + 9.10 => 10.675 => b) 9.877 c) 56700 -J- 2.33 => 4.2390558 - n e) 47583 + 224.8 > T -) i 2 . L > => 5 so m ¥ 680 => 56020 => d ) 1.400 x 2.000 => 2.8 => 0. 6 7 /OJl L Q 300 47807.8 => f) 0.0208 -f 2.3 => 0.0090435 => / ai i 'tD ~ 41 tOi SI s i n . oo°/o 12. An high school experiment to determine the molar mass of magnesium metal gave a value of 25.8 g. If the accepted value for this mass is 24.3 g, what is the percentage error in this experiment ? &rrVr o s. f ? - ? * ? ? o • <5; U 2 4.1 7 13. Identify the apparatus. Spelling counts. , 1> eua Mr a /MAI 7iiL c V o c) U Href d) ' flsf f> r h $ k \ ( i II 2 2 ^/ ^ n ? 4 U/T /(