Questions asked by Yann

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• How many grams of sodium sulfate (na2so4) are required to make 4.5 liters of a 3.0M solution?
  
• How many mL of a 3.2M NaOH solution is required to neutralize 74mL of a 12.4M HCl solution?
  
• For the equilibrium reaction X + y -> XY, the rate of the forward reaction at equilibrium is equal to 1.75 sec^(-1). What is the rate of the reverse reaction?
  
• Hydrofluoric acid, HF, has an acid dissociation constant of #6.8 * 10^(-4)# at 25 °C. At equilibrium the concentration of HF is 0.025M. a. What is the equilibrium constant expression for this dissociation? b. What is the pH of this solution?
  
• Which of the following has highest bond enthalpies? H-F C=O H-H N(triple bond)N
  
• Find entropy, enthalpy, Gibbs free energy of reaction at 298K. Find if it is exothermic and whether it is spontaneous? C3H8 + 502 -> 3CO2 + 4H2O
  
• Use Hess's Law and the following information to calculate the change in enthalpy for the reaction 2C + H2 -> C2H2?
  
• Find overall reaction for a galvanic cell that will have the highest cell potential. What is the overall potential of the cell? Which two equations do I use?
  
• Help! Let f(x) be a function with domain [-3, ∞ ) and range (- ∞ , 2). If g(x) = f^-1 (x) (aka. g(x) is the inverse of f(x)), then what is the domain of g(x+4)-7 ?
  
• Simplify the following? csc(arctan(sec(arccos(-3/5))))
  
• If cot (π/2 - x) = -3/4 , what is sec^2(x)?
  
• Find all angles x [0, 2π), such that cos(2x) = 2sin(x) = -3 ?
  
• What is the inverse of the function #f(x) = 7log_4(x+3) - 2#? It is #7log_4 (x+3) - 2#, if that clears any confusion.
  
• Use#cos(x/2) * cos(x/4) * cos(x/8)# and the half angle formula #[cos(A/2) = sqrt(1+cosA)/2]# to show #2/π = sqrt(2)/2 * (sqrt(2+sqrt2))/2 ...# How?
  
• Let z = 1-i. Find abs(z) ... How?
  
• Solve for x: tan^3(x) - 3tan(x) = 0 Solve for [0, 2π) ... How?
  
• Solve for x: arctan(x) = arccos(5/13) Solve for [0, 2π)... How?
  
• Solve: x^(-3) = 8 How do I solve for x?
  
• Urgent! The polynomials #ax^3-3x^2+2x-3# and #ax^2-5x+a# when divided by #x-2# leave remainders of #p# and #q# respectively. Find the value of #a# if #p=3q#. How? Urgent thanks!
  
• Urgent! Help! A cubic polynomial has zeros at x=-1, x=1, and x=3. It has a y-intercept of -6. What is the remainder when we divide this polynomial by x^2+1 ??
  
• Help! Use Gauss-Jordan elimination (row reduction) to find all solutions to the following system of linear equations? 2x + 3y - z = 3 - x + 4y = 9 4x - y - z = -7 How? Help!
  
• Let P(x) be a real polynomial of degree ≤4 such that there are at least 5 distinct solutions to P(x) = 5. Find P(5). How???
  
• If f(x) = 2x + 1 and g(f(x)) = 4x^2 + 4x + 3 , find g(x), given that g(x) is in the form of ax^2 + bx + c. How?
  
• Urgent! There is a ferris wheel of radius 30 feet. When the compartments are at their lowest, it is 2 feet off the ground. The ferris wheel makes a full revolution in 20 seconds. Using a cosine function, write an equation modelling the height of time?
  
• Help! Rotate the axis to eliminate the xy-term in the equation then write the equation ins standard form. x^2-4xy+4y^2+5sqrt(5)+1=0 Help!?
  
• Help! Rotate the axis to eliminate the xy-term in the equation then write the equation ins standard form. #x^2-4xy+4y^2+5sqrt(5)y+1=0# Help!?
  
• What are [computer] keyboards made of? As in materials used in keys or the board itself. Thanks!
  
• When ammonium sulfate is heated with solution X, ammonia gas is given off. Is solution X HCl or NaOH?
  
• If you cover the tip of a shoot in opaque black aluminium foil, towards which direction does the shoot grow? Or does it even grow at all?
  
• Find the area bounded by the curve y=e^(x/3) , the tangent line which is y=1/3 e^(3)x - 2e^3 and the x-axis?
  
• There are usually fewer stomata found on the upper surface of a leaf. Suggest why this is beneficial to a plant?
  
• What burns to produce one product? What does not change litmus paper (either way)? a. carbon dioxide b. carbon monoxide
  
• How many even numbers less than 500 can be formed using the digits 1,2,3,4,5? Each digit can only be used once.
  
• The fundamental frequency of a closed tube is the same frequency as the 2nd harmonic of a stretched string. The mass per unit length of the string is 6.10x10^-4 kg/m. The tension in the string is 48.0N...?
  
• How do you transform y=1/x to y= (3x-2)/(x+1) ?
  
• Assuming that all of the elastic potential energy is transferred to kinetic energy, what speed will a 0.57kg ball leave a spring that is compressed 0.13m?
  
• A 2.6kg car is rolling down a frictionless incline that makes an angle of 23º to the horizontal. The initial speed of the car is 4.3m/s. What is the speed of the car 26m down the incline?
  
• Could someone explain the lewis structure diagram of covalent compound Al2Cl6?
  
• The summit of mount everest can be at a temperature of -50ºC and the pressure at its summit is roughly 1/3 that at sea level. The density of air at sea level is about 1.25kg/m^3. Calculate the density of air at the top of the mountain?
  
• The temperature of a fixed mass of an ideal gas goes from 40ºC to 80ºC at a constant volume. If the initial pressure was x, what is the new pressure?
  
• Calculate the mean-square speed, of krypton atoms in a sample of gas at a temperature of 22ºC?
  
• The molar mass of carbon dioxide is 0.045kg/mol. Calculate the density of the gas when the temperature is 273K and the pressure is 120000Pa..?