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1. Classify each as a pure substance, a solution, or heterogenous mixture: a gold coin, a cup of coffee, a wood plank
What ambiguities are there in answering part A from the descriptions given?
2.Two students determine the percentage of lead in a sample as a laboratory exercise. The true percentage is 22.52 %. The student's results for three determinations are as follows:
1. 22.52, 22.48, 22.54
2.22.64,22.58,22.62
(a) calculate the average percentage for each set of data, and tell which is more accurate based on the average.
(b) (Calculate the average value for each data set, then calculate the average value of the absolute deviations of each measurement from the average) Which set is more precise?
3. 2.Read the following description of the element zinc, and indicate which are physical properties and which are chemical properties. Zinc is a silver-gray- colored metal that melts at 420 Degrees Celsius. When zinc granules are added to dilute sulfuric acid, hydrogen is given off and the metal dissolves. Zinc has a hardness on the mohs scale of 2.5 and a density of 7.13 g/cm^3 at 25 degress Celcius. It reacts slowly with oxygen gas at elevated temperatures to form zinc oxide, ZnO
4. A cube of osmium metal 1.500 cm on a side has a mass of 76.31 g at 25 Degree Celcius. What is it's density in g/cm^3 at this temperature? (b) The density of titanium metal is 4.51 g/cm ^3 at 25 degree celcius. What mass of titanium displaces 65.8 mL of water at 25 degrees celcius? (c) The density of benzene at 15 degrees celcius is ).8787 g/mL. Calculate the mass of 0.1500 L of benzene at this temperature.
What ambiguities are there in answering part A from the descriptions given?
2.Two students determine the percentage of lead in a sample as a laboratory exercise. The true percentage is 22.52 %. The student's results for three determinations are as follows:
1. 22.52, 22.48, 22.54
2.22.64,22.58,22.62
(a) calculate the average percentage for each set of data, and tell which is more accurate based on the average.
(b) (Calculate the average value for each data set, then calculate the average value of the absolute deviations of each measurement from the average) Which set is more precise?
3. 2.Read the following description of the element zinc, and indicate which are physical properties and which are chemical properties. Zinc is a silver-gray- colored metal that melts at 420 Degrees Celsius. When zinc granules are added to dilute sulfuric acid, hydrogen is given off and the metal dissolves. Zinc has a hardness on the mohs scale of 2.5 and a density of 7.13 g/cm^3 at 25 degress Celcius. It reacts slowly with oxygen gas at elevated temperatures to form zinc oxide, ZnO
4. A cube of osmium metal 1.500 cm on a side has a mass of 76.31 g at 25 Degree Celcius. What is it's density in g/cm^3 at this temperature? (b) The density of titanium metal is 4.51 g/cm ^3 at 25 degree celcius. What mass of titanium displaces 65.8 mL of water at 25 degrees celcius? (c) The density of benzene at 15 degrees celcius is ).8787 g/mL. Calculate the mass of 0.1500 L of benzene at this temperature.