Test 5 CHM1045C Fa06 - answers

Test 5 CHM1045C Fa06 - answers - Name. Recitation Section....

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Name……………………………………………………………… Recitation Section………………. Test 5 CHM1045C Monday December 4 th 2006 All questions carry the same marks. Do the easiest ones first. Here are some formulas and constants. No of moles = mass(g)/formula mass : Molarity = No of moles of solute/No of liters of solution PV = nRT : R = 8.3J/K.mol : at 273K 1mol of gas occupies 22.4L : N A =6 x 10 23 particles/mol Speed of light, c = 3 x 10 8 m/s : c = νλ Heat energy = mass(g) x specific heat capacity x temperature change(K) 1 Is photosynthesis a physical or a chemical change? Chemical 2 The SI unit of length is the metre. How many nanometres make 1m? 1 billlion 3 Body temperature is 98 o F, 37 o C. What is its value in kelvins? 37 + 273 = 310K 4 MgCO 3 has a mass fraction of Mg of 0.29. How much Mg is there in 30g of MgCO 3 ? 0.29 x 30 = 8.7g 5 60 28 Ni is the symbol for one isotope of nickel. How many electrons, protons and neutrons (separately) are there in one atom of Ni? At no 28. 28e, 28p, (60-28) = 32n 6 What are the names of CaS Calcium sulfide Al(NO 3 ) 3 ? Aluminum nitrate 7 What are the formulas of potassium sulfate K 2 SO 4 magnesium bromide? MgBr 2 8 The empirical formula of hexane is C 3 H 7 . Its molar (formula) mass ( M ) is 86. What is its molecular formula? (C = 12, H = 1)
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Formula mass for C 3 H 7 is (3x12 + 7x1) = 43: 86/43 = 2, so molecular formula is 2 x C 3 H 7 = C 6 H 14
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Test 5 CHM1045C Fa06 - answers - Name. Recitation Section....

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