Brian Mutembei

Newton’s Law of Cooling assume that the rate of cooling is proportional to the temperature difference (M-T) between the medium (environment) temperature M and the object’s temperature T, which leads to the equation: dT/dt = k(M – T) where k is the constant of proportionality. Do the following: Solve this equation for T. If a pot of boiling water (100 degree Celsius) is removed from the heat and allowed to cool. After ten minutes the temperature is 75 degree C, and in another five minutes it has dropped to 65 deg. What is the temperature of the kitchen?

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Derive a titration curve for 50.00 mL of 0.0100 M Sr2+ with 0.0200 M EDTA in a solution buffered to pH 11.0. Calculate pSr values after the addition of 0.00, 10.00, 24.00, 24.90, 25.00, 25.10, 26.00, and 30.00 mL of titrant.

EXPERT ANSWER Initial [Sr2+] = 0.0100 M Initial volume of Sr2+ solution = 50.00 mL Initial milimoles of Sr2+ = 50 * 0.010 = 0.5 mmoles At pH = 11, 4 of EDTA = 0.85 KSrY = 4.3×108 Conditional constant, K’SrY =  4 * KSrY = 0.85 * 4.3×108 = 3.655×108 When 0.0 mL EDTA is added – [Sr2+] = 0.010 M …

Derive a titration curve for 50.00 mL of 0.0100 M Sr2+ with 0.0200 M EDTA in a solution buffered to pH 11.0. Calculate pSr values after the addition of 0.00, 10.00, 24.00, 24.90, 25.00, 25.10, 26.00, and 30.00 mL of titrant. Read More »

Which analyte will have a greater change of pAg at equivalence point region? I- (iodide) or IO3-(iodate)?

EXPERT ANSWER Answer: This is the Iodometric involes indirect titration of iodine liberated by reaction with an analyte,whereas iodometry involes direct titration using iodine as titrant. Redxc titration using sodium thiosulphate as a reducing agent is known as iodometric titration since it is used sphecifically titrate iodine.In this titratio starch is used as indicator since …

Which analyte will have a greater change of pAg at equivalence point region? I- (iodide) or IO3-(iodate)? Read More »

1. A gas tank containing an ideal gas is exposed to the atmosphere. During noontime when the heat due to exposure to the sun’s rays is maximum, the temperature of the gas is 60°C. In the afternoon just before the sun sets, the gas gets cooler and its temperature drops to 17 °C and the pressure in the tank is 950 kPa. What was the pressure of the gas during noontime? 2. A gas tank containing 4kg of an ideal gas (R = 518 J/kg°K) has pressure of 300kPa and temperature of 26°C. If the pressure is changed to 340kPa, how many kilograms of the gas must be removed so that the pressure returns to the original pressure at 300kPa? 3. A tank with a volume of 0.5m contains an ideal gas at 100kPa and 298°K. Another tank contains the same kind of gas at 182kPa and 380°K. If the two tanks are connected by a pipe with a valve, and the valve is opened the pressure and temperature of the gas in both tanks are 140 kPa and 340°K, respectively. Compute for the volume of the second tank. 4. A reservoir contains 2.83 m of carbon monoxide at 6895 kPa and 23.6°C. an evacuated tank is filled from the reservoir to a pressure of 3497kPa and a temperature of 12.4 °C. while the pressure in the reservoir decreases to 6205 kPa and the temperature to 18.3 °C. What is the volume of the tank? R for CO is 296.92 J/kg. Kº

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