Answers created by Sam

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• What is the ground state electron configuration for Zn ?
  
• 3.55 moles #H_2# (g), 1.25 moles #CO# (g), and an unknown number of moles #N_2# (g) were placed into a 5.00 L flask at #25.0^oC#. Given the density of this gas mixture to be 19.92 g/L, how many moles of #N_2# were in the flask?
  
• 58.5 is 13% of what number?
  
• How is carbocation formed?
  
• What is the pH of a 0.0453 M #HCl# solution?
  
• How can you identify alkenes?
  
• Question #f83f5
  
• What mass of sodium benzoate should be added to 140.0 mL of a 0.15 M benzoic acid solution to obtain a buffer with a pH of 4.25?
  
• The half-life of bromine-74 is 25 min. How much of a 6.0 mg sample is still active after 75 min?
  
• How many moles of ethylene (#C_2H_4#) can react with 12.9 liters of oxygen gas at 1.2 atmospheres and 297 Kelvin?
  
• Why are carbocations unstable?
  
• How do you find a standard form equation for the line (2,-1) (0,-4)?
  
• How can you test for ketones?
  
• How many millliters of 2.75 M #H_2SO_4(aq)# are needed to react completely with 47.5 g of #BaO_2(s)#?
  
• How can alkenes be used to make ethanol?
  
• How many liters of carbon dioxide can be produced if 37.8 grams of carbon disulfide react with excess oxygen gas at 28.85 degrees Celsius and 1.02 atmospheres?
  
• How many moles of copper are equivalent to #3.44*10^23# atoms of copper?
  
• The half-life of cobalt-60 is 5.26 years. If 50 g are left after 15.8 years, how many grams were in the original sample?
  
• How do you convert 225 mmHg into atmospheres?
  
• What are the empirical and molecular formulas of nicotine?
  
• How do you find the vertex of the parabola #y=2x^2-5#?
  
• What is carbocation intermediate?
  
• The freezing point of an aqueous sodium chloride solution is -0.20°C. What is the molality of the solution?
  
• How many liters are in 16 grams of #H_2# at STP?
  
• The freezing point of an aqueous solution is -2.79°C. What is the boiling point of this solution?
  
• Helium occupies 2.40 L at 123°C. What would the volume of the same sample of gas be at 23°C?
  
• How do you find the vertex and intercepts for #y = (1/8)(x – 5)^2 - 3#?
  
• What is 306,000,0000 in a scientific notation?
  
• Which Lewis electron-dot diagram is correct for a #"S"^(2-)# ion?
  
• A solution is prepared to be 0.1475 M in Sr(OH)2. How do you find the [H3O+], [OH‐], pH, and pOH?
  
• The titration of 20.0 mL of an unknown concentration #H_2SO_4# solution requires 83.6 mL of 0.12 M #LiOH# solution. What is the concentration of the #H_2SO_4# solution (in M)?
  
• What mass of #SbCl_3# can be produced from the reaction of 3.570 L of chlorine at STP reacting with an excess of antimony in the reaction #Sb+Cl_2 -> SbCl_3#?
  
• What is the point of intersection of the lines #y = 2x + 4# and #x + y = -11#?
  
• An ideal gas sample is confined to 3.0 L and kept at 27°C. If the temperature is raised to 77°C and the initial pressure was 1500 mmHg, what is the final pressure?
  
• What is the weight in grams of #3.36 * 10^23# molecules of copper sulfate #CuSO_4#?
  
• If you had a 100-gram sample of plutonium, how much would still remain in 43 years?
  
• How do you solve #2(6 - x) = x(x + 5) # using the quadratic formula?
  
• A 12.0 L sample of argon gas has a pressure of 28.0 atm. What volume would this gas occupy at 9.70 atm?
  
• What does the number prefix tell you in the name of a branched alkane?
  
• Polonium-214 has a relatively short half life of 164 s. How many seconds would it take for 8.0 g of this isotope to decay to 0.25 g?
  
• How do you prove #cos(x+y)cos(x-y)= cos^2x - sin^2y#?
  
• At approximately what pressure will water be a vapor a 0°C?
  
• How many grams of #Cl# are in 515 g of #CaCl_2#?
  
• One of the lines in the emission spectrum of the hydrogen atom has a wavelength of 656.7 nm, how would you Identify the value of n initial for the transition giving rise to this emission?
  
• What is the vertex form of #y=4x^2-x+4#?
  
• What is the pH of a 0.0067 M KOH solution?
  
• What is the equation to find pH and pOH?
  
• What is the lewis structure of #NO^+#?
  
• The mass defect for a Li-6 nucleus is -0.03434 g/mol. How do you calculate the atomic mass of Li-6?
  
• What is the standard cell notation of a galvanic cell made with silver and nickel?
  
• What is a property of all alkanes?
  
• How many grams of #K_2CO_3# are needed in order to produce 2.0 mol #K_2O#?
  
• What is half chair conformation?
  
• What is the #"pH"# for #2.5 xx 10^(-6) "M"# #"HCl"#?
  
• How do London dispersion forces increase?
  
• How do you find vapor pressure?
  
• What is the half-life of 20 g of a radioactive sample if 5 g remain after 8 minutes?
  
• A 100.0 mL sample of .10 M #NH_# is titrated with .10 M #HNO_3#. What is the pH of the solution after the addition of 150.0 mL of #HNO_3#?
  
• How do you write #f(x)=-x^2+4x+6# in vertes form?
  
• What kind of reaction is #2Fe(s) + O_2(g) -> 2FeO(s)#?
  
• What is the vertex of the parabola #y=(x-8)^2#?
  
• Question #e901d
  
• What is the Lewis structure of #BF_4^-#?
  
• How do you rationalize the denominator and simplify #(1+sqrt2)/(3-5sqrt2)#?
  
• How do alkoxide ions form?
  
• How do you solve #x + 3y = 6# and #2 x + y = 4# using substitution?
  
• How do you write the point-slope form of the equation below that represents the line that passes through the points (−3, 2) and (2, 1)?
  
• How do you find the midpoint of the line segment joining (2, -3) and (5, -4)?
  
• What is the the vertex of #y =-x^2 - 4x - 10#?
  
• How do you graph #y = x + 2# by plotting points?
  
• What is a secondary alcohol?
  
• How do you write an equation of a line going through (1,2) (-1,2)?
  
• What is the pH of a 0.85 M #NH_4Cl# solution?
  
• Question #9abd1
  
• How do you write a quadratic equation with Vertex: (-1,-3) x-intercept: 2?
  
• If the mole fraction of #NaCl# in an aqueous solution is 0.0927, what is the percent by mass of #NaCl#?
  
• Sodium-24 has a half-life of 15.0 hours. Suppose you had a sample containing 0.010 moles of Na-24. How many hours would be required to reduce your sample to 6.25 x 10^-4 moles?
  
• What frequency does a photon of wavelength #4.5 * 10^-4# #m# have?
  
• What is the standard form of the equation of the parabola with a directrix at x=5 and a focus at (11,-7)?
  
• In 5.49 seconds, 1.20 g of argon-35 decays to leave only .15 g. What is the half life of argon-35?
  
• How do you graph #Y=(x-4)^2#?
  
• The product of two consecutive even integers is 168. How do you find the integers?
  
• How do you name meso compounds?
  
• Question #269de
  
• How do you do addition reactions of alkenes?
  
• How do you name cycloalkanes with halogens?
  
• What is the number of moles in 9.63 L of #H_2S# gas at STP?
  
• How are aldehydes different from ketones?
  
• Question #7ee1d
  
• If the density of an unknown gas #Z# 4.50 g/L at STP, what is the molar mass of gas #Z#?
  
• Question #3f2c0
  
• What is the molecular shape of acetylene?
  
• What is the pH and pOH of a #1.5 * 10^-3# M solution of sulfuric acid (#H_2SO_4#)?
  
• What is the effect of changing #y = 3x-2# to the equation #y = 3x+ 2#?
  
• How many valence electrons does #NO_3^-# have?
  
• How do you rationalize the denominator and simplify #sqrt18/sqrt3#?
  
• You have a compound that is composed of 62.0 grams #C#, 12.15 grams #H#, 13.771 grams #O# and 12.059 grams #N#. What is its empirical formula?
  
• What is the Henderson-Hasselbalch equation? How is it used in chemistry?
  
• The pH of a solution is 5.6. What are the hydrogen and hydroxide concentrations?
  
• What is the value of #cos (pi/3) - sin((3pi)/2)#?
  
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