# Flashcards › Gas Laws & Thermochem review part 2

## A sample of gas is collected by water displacement at 600.0 mm Hg and 30*C. What is the partial pressure of the gas? 568.2 mmHg A sample of nitrogen is collected by water displacement at 730.0 mm Hg and 20*C. What is the partial pressure of the nitrogen? 717.2 mm Hg Gay-Lussac recognized that at constant temperature and pressure, the volumes of gaseous reactants and products can be expressed as ratios of small whole numbers The principle that under similar pressures and temperatures, equal volumes of gases contain the same number of molecules is attributed to Avogadro Equal volumes of diatomic gases under the same conditions of the temperature and pressure contain the same number of molecules The expression V=kn is a statement of Avogadro's principle Avogadro's principle led to the realization that the realization that the molecules of some substances were made of more than one atom The standard molar volume of a gas at STP is 22.4 L At STP, the standard molar volume of a gas of known volume can be used to caclate the number of moles of gas The ideal gas law is equivalent to Avogadro's law when the pressure and the temperature are constant Which is a common unit for the ideal gas constand R? L*atm/mol*k What is the value of the gas constant? 0.0821 L*atm/mol*k The value of R, the ideal gas constant, can be calculated from measured values of a gas's pressure, volume, temperature, and molar amount The gas constant, R, has the value of 0.0821 L*atm/mol*k Calculate the approximate temperature of a 0.50 mol sample of gas at 750 mm Hg and a volume of 12L. 15*C A sample of gas at 25*C has a volume of 11L and exerts a pressure of 660 mm Hg. How many moles of gas are in the sample? 0.39 mol What is the approximate volume of gas in a 1.50 mol sample that exerts a pressure of 0.922 atm and has a temperature of 10.0*C? 37.8L A gas sample with a mass of 0.68 g is collected at 20*C and 722.5 mm Hg. The volume is 350 mL. What the molar mass of the gas? 50 g/mol A gas sample with a mass of 0.934g is collected at 20.0*C and 733.5 mm Hg. The volume is 200.0mL. What is the molar mass of the gas? 116g/mol A gas sample with a mass of 5.16g is collected at 28*C and 740 mm Hg. The volume is 1.00L. What is the molar mass of the gass? 130g/mol A gas sample with a mass of 0.250g is collected at 150.0*C and 720.0 mm Hg. The volume is 85.0mL. What is the molar mass of the gas? 108g/mol A gas sample with a mass of 12.8g exerts a pressure of 1.2 atm at 15*C and a volume of 3.94L. What is the molar mass of the gas? 64g/mol If n and T are constant, the ideal gas law reduces to Boyle's law When the ideal gas law reduces to PV=k, the expression is equivalent to Boyle's law When the ideal gas law reduces to V=kT, the expression is equivalent to Charles's law For reactants or products that are gases the coefficients in the chemical equation indicate volume If the volume of the gaseous reactants and products in the equation 2C2H6+7O2--&amp;amp;amp;gt; 4CO2+6H2O are measured at 1 atm and 25*C, the substance that could not be included in the volume relationship has what formula? H2O In a chemical equation, the coefficients for reactants and products that are gases indicate volume ratios What law helps ecplain the volume ratios in a chemical reaction? Gay-Lussac's law of combining volumes Columes of gaseous reactants and products in a chemical reaction can be expressed as ratios of smal whole numbers if constant temperature and pressure are maintained According to Avogadro's law, in a chemical equation equal volumes of gases contain equal numbers of molecules The ratios of the volumes of the gaseous reactants and products in a chemical reactio at constant temperature and pressure can be determined from the coefficients in the balanced equation In the reaction 2H2(g)+O2(g)=2H2O(g), what is the volume ratio of O2 to H2O? 1:2 In the reaction H2(g)+Cl2=2HCl, what is the volume ratio of Cl2 to HCl? 1:2 The equation for the production of methane is C+2H2(g)--&amp;amp;gt;CH4(g). How many liters of hydrogen are needed to produce 20L of methane? 40L What is the number of moles of H2 produced when 23g of sodium react with water according to the equation 2Na(s)+2H2O(l)--&amp;amp;gt;2NaOH(aq)+H2(g)? 0.50 mol What determines the average kinetic energy of the molecules of any gas? temperature The equation Ma Va^2=Mb Vb^2 is an expression of Graham's law A sample of hydrogen gtas diffuses 3.8 times faster than an unknown gas diffuses. What is the molar mass of the unknown gas since hydrogen is 1.0079g? 28g/mol Which of the following is a measure of the average kinetic energy of the particles in a sample of matter? temperature In what units is temperature measure? kelvins How is a celsius temperature reading converted to a Kelvin temperature reading? by adding 273.15 The greater the kinetic energy of the particles in a sample of matter, the higher the temperature is Which of the following best describes heat? the energy transferred betweensamples of matter because of a difference in their temperatures What is the heat required to raise the temperature of 1g of a substance by 1*C or 1K? Specific Heat Which expression defines specific heat? Heat/Mass x Temperature change How much energy is absorbed as heat by 20g of gold when it is heatead from 25*C to 35*C? The specific heat of gold is 0.13 J/g*C. 26J A 5.0 sample of silver is heated from 0*C to 35*C and absorbs 42J of energy as heat. What is the specific heat of silver? 0.24J/g*C The quantity of energy released or absorbed as heat during a chemical reaction is called the heat of reaction What is the difference between the enthalpies of the products and the reactants? change of H More AP level