Examples *0.1356 (4 significant figures) -> Round answer to 2 significant figures *0.1356 -> 0.14 *314.705 (6 significant figures) -> Round number to 4 significant figures. *314.705 -> 314.7 *0.0035771 (5 significant figures) -> Round to 3 significant figures. *0.0035771 -> 0.00358 *500‚000 (1 significant figure) -> Write this number to have 3 significant figures. *500‚000 - 5.00 x 10^5 *39.501 -> Round to 2 significant figures. *39‚501 -> 4.0 x 10 *0.054961 -> Round
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toluene respectively. 2) In a separate test tube add 4 ml of 0.01mol L-1 KMnO4 to 2 ml of 2mol L-1 H2SO4 3) Add 1 ml of this acidified KMnO4 solution to each of the test tubes containing the hydrocarbons. Shake each test tube gently and record any change that takes place in the aqueous layer over about 5 minutes. Reaction of hydrocarbons with bromine water: 1) Into three separate‚ labeled test tubes place 1 ml of cyclohexane‚ cyclohexene and toluene respectively. 2) Add 1 ml of bromine water
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ν = cλ 1) C) νλ = c D) λ = c ν E) ν + λ = c 2) The photoelectric effect is __________. A) a relativistic effect B) the ejection of electrons by a metal when struck with light of sufficient energy C) the darkening of photographic film when exposed to an electric field D) the production of current by silicon solar cells when exposed to sunlight E) the total reflection of light by metals giving them their typical luster 2) 3) Low-frequency electromagnetic fields with potential
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precipitation is carried out slowly‚ which can be done by dissolving Ca2+ and C2O42- in acidic solution & gradually increasing the pH by thermal decomposition of urea‚ Co(NH2)2. Equation : Co(NH2)2 + 3H2O CO2 + 2NH4+ + 2OH- Methyl red indicator: [below pH 4.8 – red ; above pH 6.0 - yellow] Sample experimental Data Funnel #1 Funnel#2 Average Mass of glass funnel‚ initial (grams) 35.2653 34.5269 34.8961 Mass of glass funnel + ppt. after drying (grams) 35.6653 34.9569 35.3111 Mass of product
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In the Lewis symbol for a fluorine atom‚ there are __________ paired and __________ unpaired electrons. A) 4‚ 2 B) 0‚ 5 C) 2‚ 5 D) 6‚ 1 E) 4‚1 2. Which of the following would have to gain two electrons in order to achieve a noble gas electron configuration? O Sr Na Se Br A) Sr B) Br C) Sr‚ O‚ Se D) Na E) O‚ Se 3. The electron configuration of the S2- ion is __________. A) [Ne]3s23p2 B) [Ne]3s23p6 C) [Kr]3s22p-6 D) [Ar]3s23p2 E) [Ar]3s23p6 4. The ion NO- has __________
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0 gram iron rod to the solution and observe the reaction. 2 Fe + 3 CuSO4 = 3 Cu + Fe2(SO4)3 The new product is iron (III) sulfate‚ it contains the Fe 3+ ion which is brown. Lead (II) nitrate and potassium iodide solutions Pour about 2.0 mL of lead (II) nitrate into the test tube. Add 5 to 10 drops of potassium iodide solution to the test tube and record your observations of the reaction. Pb(NO3)2 + 2 KI = 2 KNO3 + PbI2 2. Magnesium metal and hydrochloric acid solution Place one
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or trans) CH2CH3 C) CH3 CH2=CCH2CHCH2CH3 CH3 CH2 D) CH3CH2CCHCH2CH3 CH3 CH3 E) CH3CH2CHCHCH=CH2 CH3 Ans: B 241 Keghan Chapter 8 Topic: Structure Elucidation 2. Ozonolysis of compound Z yields the products shown below. What is the structure of Z? O Z 1) O3 2) Zn‚ HOAc O 2HCH + CH3CCH2CH O I II III O H IV A) B) C) D) E) O V I II III IV V Ans: B 242 Keghan Chapter 8 Topic: Structure Elucidation 3.
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and formed products based on a BALANCED chemical equation. Mass Molar Mass Mole Coeff Bal Eqn Mole Molar Mass Mass Example 2 • The Haber Process involves reacting gaseous nitrogen and gaseous hydrogen to form ammonia. Determine the mass in grams of hydrogen gas required to form 1.00 x 103 g ammonia. Your Turn 2 • If you react 52.9 g of potassium chlorate (KClO3) with excess phosphorus‚ what mass of tetraphosphorus decoxide (P4O10) would be produced. KClO3
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Isotope: element variations with different atomic mass but same atomic number Isotopic Abundance: the relative amount in which each isotope of an element Calculating: given 2 isotopes of an element [B: 10.01u] [B: 11.01u] 1) Given average atomic mass: 10.81u If given percentages‚ you can find average atomic mass by adding each portion 2) Set variables for unknown values Let x represent % abundance for 10/5 B Let 1-x represent % abundance for 11/5 B Calculate: 10.01x+(1-x)11.01=10.81 10.01x+11.01-11
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(2) (b) A gas oil fraction from the distillation of crude oil contains hydrocarbons in the C15 to C19 range. These hydrocarbons can be cracked by strong heating. (i) Write the molecular formula for the alkane with 19 carbon atoms. (ii) Name the type of reaction involved in cracking. (iii) Write an equation for one possible cracking reaction of the alkane C16H34 when the products include ethene and propene in the molar ratio 2:1 and only one other compound. (4) (Total 6 marks) 2. A compound
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