answer key to chem

answer key to chem - Exam 1 ANSWER KEY 1) Describe the...

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Exam 1 ANSWER KEY 1) Describe the following as either a physical or chemical change: a- Dissolving salt in water is an example of which type of change?(_ physical_ ____ __) b. Frozen orange juice is reconstituted by adding water to it (_ _ ______ physical__________) c. Chopping timber for heating purpose of houses (_ _ ____ physical____________) d. Burning term papers after finishing the semester (____ chemical_____________) e. Metallic bridge got rusted after exposure to lot of salt (__ _ __ chemical________) 2) Convert the following number in scientific notation with the requested number of significant figures: a. 0.00034 512= (2 significant figures). 3.5 x 10 -4 b. 12400 62=(5 signifiant figures). 12401 c. 12400 62=(5 signifiant figures). 12401 d. 45 5.01=(2 signifiant figures). 460 or 4.6 x 10 2 e. 0.0000000876 5= (3 significant figures). . 00000000876 or 8.76 x 10 -8 f. 31 × 152.3= (4 sig Figs) 4721.3 (calculator answer) so 4721 3) A thermometer reading of a patient was 102.8 o F. Convert this temperature to degree Celsius ( o C) and Kelvin (K)? o C = ( o F – 32) 5/9, K= 273.15 + o C o C = 102.8 – 32 * (5/9) = 39.33, K= 273.15 + 39.33= 312.45 4) Name the following compounds: a. P 2 O 3 : diphosphorus trioxide b. B(OH) 3: Boron Hydroxide c. FeCl 2 : Iron (II) Chloride d. AgNO 3 : Silver (I) Nitrate
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e. Na 2 CO 3 .3H 2 O: Sodium carbonate trihydrate 5) Write the formula of the following compounds: a. Hydrobromic acid : HBr b. Calcium sulfide: CaS c. Zinc(II) chloride tetrahydrate: ZnCl 2 . 4H 2 O d. Lead(II) carbonate: PbCO 3 e. Dinitrogen monoxide: N 2 O 6) Fill the following table with the atomic and mass numbers ( use periodic table provided) and number of protons, electrons, and neutrons of the following atom and ion: Symbol Atomic Number Mass Number # of protons # of electrons # of neutrons Mg 2+ 12 24 12 12 – 2= 10 24 – 12= 12 P 3- 15 31 15 15+3= 18 31 – 15= 16 Co +2 27 59 27 27 – 2= 25 59 – 27= 32 K +1 19 39 19 19 – 1= 18 39 – 19 = 20 Cl -1 17 35 17 17+ 1= 18 35. 7) Potassium sulfite (K 2 SO 3 ) is often used in fire work products. Calculate the number of atoms for K, S, and O in 500 g of Potassium sulfite? 39.10 * 2 + 32.07 * 1 + 16.00 * 3 =
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answer key to chem - Exam 1 ANSWER KEY 1) Describe the...

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