Why is it necessary to measure the temperature of water when using it to calibrate a volumetric pipet? I: Mass is temperature-dependent II: Volume is temperature-dependent III: Density is temperature-dependent

Why is it necessary to measure the temperature of water when using it to calibrate a volumetric pipet? I: Mass is temperature-dependent II: Volume is temperature-dependent III: Density is temperature-dependent

Living by Chemistry

2nd Edition

ISBN:9781464142314

Author:Angelica M. Stacy

Publisher:Angelica M. Stacy

ChapterU5: Fire: Energy , Thermodynamics, And Oxidation-reduction

Section: Chapter Questions

Problem 5STP

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During a recent winter month in Sheboygan, Wisconsin, it was necessary to obtain 3500 kWh of heat provided by a natural gas furnace with 89% efficiency to keep a small house warm (the efficiency of a gas furnace is the percent of the heat produced by combustion that is transferred into the house). (a) Assume that natural gas is pure methane and determine the volume of natural gas in cubic feet that was required to heat the house. The average temperature of the natural gas was 56 F; at this temperature and a pressure of 1 atm, natural gas has a density of 0.68 1 g/L. (b) How many gallons of LPG (liquefied petroleum gas) would be required to replace the natural gas used? Assume the LPG is liquid propane [ C3H8 : density, 0.5318 g/mL; enthalpy of combustion, 2219 Id/mo for the formation of CO2(g) and H2O(l) ] and the furnace used to burn the LPG has the same efficiency as the gas furnace. (c) What mass of carbon dioxide is produced by combustion of the methane used to heat the house? (d) What mass of water is produced by combustion of the methane used to heat the house? (e) What volume of air is required to provide the oxygen for the combustion of the methane used to heat the house? Air contains 23% oxygen by mass. The average density of air during the month was 1.22 g/L. (f) How many kilowatt—hours ( 1kWh=3.6106 J) of electricity would be required to provide the heat necessary to heat the house? Note electricity is 100% efficient in producing heat inside a house. (g) Although electricity is 100% efficient in producing heat inside a house, production and distribution of electricity is not 100% efficient. The efficiency of production and distribution of electricity produced in a coal-fired power plant is about 40%. A certain type of coal provides 2.26 kWh per pound upon combustion. What mass of this coal in kilograms will be required to produce the electrical energy necessary to heat the house if the efficiency of generation and distribution is 40%?
Dinitrogen monoxide, N2O, reacts with propane, C3H8, to farm nitrogen, N2; carbon dioxide. CO2; and water, H2O. Write a balanced chemical equation for this reaction, treating all substances as gases. Include phases in your equation. Two reservoirs, separated by a closed valve (of negligible volume), are filled with the reactants (one on each side). The pressure of N2Ois measured to be 1.4atm. The pressure of C3H8is measured to be 1.2atm. Each reservoir has a capacity of 1.0L, and the temperature of the system is mg src=Images/HTML_99425-13-98QAP_image001.jpg alt="" align="top"/> e valve between the reservoirs is opened, and the chemical reaction proceeds. Assuming ideal gas behavior and constant temperature, what is the partial pressure of CO2after the reaction is complete? What is the partial pressure of N2Oafter the reaction is complete?
Redraw the cylinder in Question 77 after work has been done on the system.
Finding the volume of a flask. A student obtained a clean, dry glass-stoppered flask. She weighed the flask and stopper on an analytical balance and found the total mass to be 34.166g. She then filled the flask with water and obtained a mass for the full stoppered flask of 68.090g. From these data, and the fact that at the temperature of the laboratory the density of water was 0.9975g/mL, find the volume of the stoppered flask. a. First we need to obtain the mass of the water in the flask. This is found by recognizing that the mass of a sample is equal to the sum of the masses of its parts. For the filled, stoppered flask: Massoffilledstopperedflask=massofemptystopperedflask+massofwater,somassofwater=massoffilledflaskmassofemptyflask Massofwater=gg=g Many mass and volume measurements in chemistry are made by the method used in la. This method is called measuring by difference, and is a very useful one. b. The density of a pure substance is equal to its mass divided by its volume: Density=massvolume or volume=massdensity The volume of the flask is equal to the volume of the water it contains. Since we know the mass and density of the water, we can find its volume and that of the flask. Make the necessary calculation. Volumeofwater=volumeofflask=mL
9.16 According to Figure 9.2, the total energy supply in the United States in 2016 was 111.261015 Btu. Express this value in joules and in calories. FIGURE 9.2 Energy production and consumption (in quadrillion Btu) in the United States during the year 2016. The discussion in the text explains how to read this complex figure, which contains an enormous amount of information about the energy economy. Data come from the Department of Energy and do not always add up exactly as expected due to rounding and other issues.
A student is given a sample of a pink manganese (II) chloride hydrate. She weighs the sample in a dry, covered crucible and obtains a mass of 26.742g for the crucible, cover, and sample. Earlier she had found that the crucible and cover weighed 23.599g. She then heats the crucible to drive off the water of hydration, keeping the crucible at red heat for about 10 minutes with the cover slightly ajar. She then lets the crucible cool and finds it has a lower mass; the crucible, cover and contents then weigh 25.598g. In the process the sample was converted to off-white anhydrous MnCl2. a. What was the mass of the hydrate sample? _ghydrate b. What is the mass of the anhydrous MnCl2? _gMnCl2 c. How much water was driven off? _gH2O d. What is the percent by mass of water in the hydrate? water=massofwaterinsamplemassofhydrateinsample100 _massH2O e. How many grams of water would there be in 100.0g hydrate? How many moles? _gH2O; _molesH2O f. How many grams of MnCl2 are there in 100.0g hydrate? How many moles? What percentage of the hydrate is MnCl2? Convert the mass of MnCl2 to moles. The molar mass of MnCl2 is 125.85g/mol. _gMnCl2; _molesMnCl2 g. How many moles of water are present per mole MnCl2? _ h. What is the formula of the hydrate? _
Explain why the numbers of molecules are not identical in the left- and tight-hand bulbs shown in the center illustration of Figure 9.27.
Suppose that you are closing a cabin in the north woods for the winter and you do not want the water in the toilet tank to freeze. You know that the temperature might get as low as 30. C, and you want to protect about 4.0 L water in the toilet tank from freezing. Calculate the volume of ethylene glycol (density = 1.113 g/mL; molar mass = 62.1 g/mol) you should add to the 4.0 L water.
Define the joule in terms of SI base units.
What will be the final temperature of a mixture made from equal masses of the following: water at 25.0C, ethanol at 35.5C, and iron at 95C?
A 2.8 L balloon is warmed over a toaster, and its temperature rises from 25Cto45C. What is its final volume?