handout problems 159

# handout problems 159 - textbook The bomb was immersed in...

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HANDOUT PROBLEMS H1CH3: To prepare alum, KAl(SO 4 ) 2 • xH 2 O, aluminum is reacted with potassium hydroxide, and the product is reacted with sulfuric acid. Upon cooling, alum crystallizes from the solution. A 0.5404-g sample of alum is heated to drive off the waters of hydration, and the resulting KAl(SO 4 ) 2 weighs 0.2941 g. Determine the value of x in the formula for alum. H2CH3: A sample of impure magnesium was analyzed by allowing it to react with excess HCl solution: Mg(s) + 2 HCl(aq) MgCl 2 (aq) + H 2 (g). After 1.32 g of the impure metal was treated with 0.100 L of 0.750 M HCl, 0.0125 mol of HCl remained. Assuming that the impurities do not react with the acid, what is the mass percent of Mg in the sample? H1CH6: A chemical engineer studying the properties of fuels placed 1.500 g of a hydrocarbon in the bomb of a calorimeter and filled it with O 2 gas (see Figure 6.8 on page 190 of the
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Unformatted text preview: textbook). The bomb was immersed in 2.500 L of water and the reaction initiated. The water temperature rose from 20.00°C to 23.55°C. If the calorimeter (excluding the water) has a heat capacity of 403 J/K, what is the heat of combustion (q V ) per gram of the fuel? H1CH7: In compliance with conservation of energy, Einstein explained that in the photoelectric effect, the energy of a photon (hν) absorbed by a metal is the sum of the work function (φ), the minimum energy needed to dislodge an electron from the metal’s surface, and the kinetic energy (E k ) of the electron: hν = φ + E k . When light of wavelength 358.1 nm falls on the surface of potassium metal, the speed (u) of the dislodged electron is 6.40 x 10 5 m/s. (a) What is E k of the dislodged electron? Recall that E k = ½ mu 2 . (b) What is φ (in J) of potassium?...
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