Answers edited by Meave60

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• A sample of rhenium (Re) is #"37.40% Re-185"# and #"62.60% Re-187"#. What are the atomic masses of these isotopes? The sum of the masses of the two isotopes is #"371.9087 u"#. Find the mass of the individual isotopes.
  
• What determines whether a solid is soluble in water?
  
• What are some examples of precipitation?
  
• Question #bab32
  
• Question #47500
  
• Question #59866
  
• How much energy is required to raise the temperature of a #"36.00 g"# sample of ice from a temperature of #-30.00^@"C"# to a temperature of #"85.00"^@"C"#? The heat of fusion, #H_"f"#, of water is #"334 J/g"#.
  
• Convert the mass of your limiting reactant to a number of moles.
  
• What are the molecular, complete ionic, and net ionic equations for the reaction between lead(II) nitrate and ammonium phosphate?
  
• Question #f79bb
  
• What are dehydration synthesis reactions?
  
• How can a mutation lead to evolution?
  
• Question #de777
  
• Question #8b63a
  
• A ball of aluminum (cp = 0.897 J/g°C) has a mass of 100 grams and is initially at a temperature of 150°C. This ball is quickly inserted into an insulated cup with 100 ml of water at a temperature of 15.0°C. What will be the final, equilibrium temperature of the ball and the water?
  
• What is an example of an isotope abundance practice problem?
  
• How can matter be classified?
  
• How do covalent bonds form?
  
• How do you balance a single replacement reaction?
  
• Cl-35 has an atomic weight of #"34.9689# and Cl-37 has an atomic weight of #"36.9695#. What is the percent abundance of Cl-35?
  
• What is the rate of reaction if #"12.0 mL H"_2"# gas is produced in #"30.0 s"# at STP?
  
• Are lone pairs of electrons involved in chemical bonding?
  
• What happens when a metal reacts with an acid?
  
• A gas has a volume of 435 mL at #25^@"C"# and #"98.7 kPa"#. What would the volume of the gas be at STP?
  
• How are the nitrogenous bases attached to the sugar-phosphate backbone of DNA and RNA?
  
• Question #5f1ff
  
• How do you evaluate the expression #|b+c|- a# given that #a=-1#, #b=2#, and #c=4#?
  
• How many moles of electrons are in one kilogram?
  
• What is the net force acting on a yo-yo when it doesn't move?
  
• Question #347fb
  
• Question #df3c0
  
• What are the ways in which the mass of a body can be determined without using a laboratory balance?
  
• What type of reaction occurs when barium nitrate reacts with sulfuric acid?
  
• Is the #"O-O"# bond in #"H"_2"O"_2"# polar covalent or nonpolar covalent?
  
• Question #feca2
  
• What number is #3/4#% of 16?
  
• What is density?
  
• What is double bonding?
  
• Question #5c044
  
• Question #942bc
  
• How do you calculate mass using density and volume?
  
• Question #f1fda
  
• How many molecules of water in #"6.25 g"#?
  
• The temperature measured in an experiment was #"64.9"^@"C"#. The theoretical temperature is #"55.0"^@"C"#. What is the percent error?
  
• How do you calculate the percent yield of recrystallized product?
  
• Question #209d0
  
• Question #dd886
  
• What is the correct name for #"SO"_3"#?
  
• What is the wavelength of an electron with a velocity of #3.85xx10^6" m/s"#?
  
• A gas occupies 175 mL at a pressure of 825 torr. What is the volume when the pressure is decreased to 415 torr?
  
• Why does DNA polymerase proofread the new strand?
  
• What are the molecular, word, complete ionic, and net ionic equations for the reaction between #"AuBr"_3"# and #"H"_2"CO"_3"#?
  
• How to determine the wavelength and frequency of electromagnetic radiation?
  
• What is the first step of cellular respiration?
  
• Question #b69fa
  
• Question #942bc
  
• A container holds three gases: helium, argon, and xenon. The partial pressures are 0.450 atm helium and 0.350 atm argon. The total pressure is 3.00 atm. What is the partial pressure of xenon?
  
• Question #916e4
  
• Question #19ae7
  
• What is density?
  
• How many molecules of #"BF"_3"# are in #1.25# moles?
  
• What are the products of the reaction between the aqueous solutions of #"Na"_2"SiO"_3"# and #"Cu"("NO"_3)_2"#?
  
• What is the chemical formula of calcium chloride?
  
• Question #f2b92
  
• How do you calculate atmospheric pressure at an altitude?
  
• What is the oxidation state of chromium in the dichromate ion, #"Cr"_2"O"_7^(2-)#?
  
• What are nucleotides?
  
• How do compounds differ from their component elements?
  
• What are orbitals?
  
• What is the mass of #"0.475 mol"# of calcium arsenate, #"Ca"_3"(AsO"_4)_2"#?
  
• Are viruses living?
  
• Question #f8d64
  
• Can you explain the formation of an ionic compound from zinc and chlorine?
  
• Question #922a3
  
• What is the ionic compound with the formula Pr2(SeO4)3?
  
• Question #8855a
  
• Question #51278
  
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