Chansa

Newest questions and responses by Chansa
  1. chemistry

    Consider the information given below ΔH⁰/ kJmol-1 Enthalpy of lattice formation for CaF2 -2611 Enthalpy of hydration for Ca2+ ions -1650 Enthalpy of hydration for F- ions -506 Using the information given above, calculate the enthalpy of solution for

    asked on June 7, 2016
  2. chemistry

    Acids and bases • What is an acid? • A 500cm3 solution containing 1.9g of a weak acid HA has a pH of 3.50. Calculate the molar mass of the acid, given that it has a Ka of 2.0 × 10-6moldm-3 • Calculate the pH of the following: • 0.002moldm-3 NaOH

    asked on June 7, 2016
  3. chemistry

    a) Define the following terms: • Electronegativity • Bond polarity • Ionization energy b) What is the difference between ionic bonds, covalent bonds and polar covalent bonds? Give two examples of each c) Draw Lewis structures for each of the

    asked on June 7, 2016
  4. chemistry

    Suppose a substance has been prepared that is composed of carbon, hydrogen, and nitrogen. When 0.1156 gram of this compound is reacted with oxygen, 0.1638 gram of carbon dioxide (CO2) and 0.1676 gram of water (H2O) are collected. Assuming that all the

    asked on June 3, 2016
  5. physics

    A. State Ohm’s law B.Describe the process of electrolysis C. What is the relationship between resistance and resistivity D. What is the current through 8Ω device operating with 120V The potential difference required to pass 3A through 42Ω. E.

    asked on May 17, 2016
  6. physics

    A display sign is supported by a guy making an angle of 37o with the horizontal and by a bracket at the upper end near the vertical wall. The sign weighs 150N. Find A. The tension in wire B. The force exerted by the bracket on the sign.

    asked on May 17, 2016
  7. physics

    A ladder rests against a smooth wall (by smooth wall, we mean that the wall exerts in the ladder only a force that is perpendicular to the wall. There is no friction force). The ladder weighs 200N and its center of gravity is 0.4L from the base, where L is

    asked on May 17, 2016
  8. physics

    A display sign is supported by a guy making an angle of 37o with the horizontal and by a bracket at the upper end near the vertical wall. The sign weighs 150N. Find A. The tension in wire B. The force exerted by the bracket on the sign.

    asked on May 10, 2016
  9. physics

    A 5kg object placed on a frictionless, horizontal table connected to a string that passes over a pulley and then is fastened to a hanging 9kg object. Draw a free body diagram of both the objects. Find the acceleration of the two objects and the tension in

    asked on May 4, 2016
  10. physics

    A bag of cement of weight 325N hangs from wires as Shawn. Two of the wires make angels al=60 degrees a2=50 degrees with the horizontal. If the system is in equilibrium find the tension T1, T2 and T3 in the wires.

    asked on May 4, 2016
  11. physics

    A tire 0.5m in radius rotates at a constant rate of 200 rev/min.find the speed and acceleration of a stone lodged in the tread of the tire ( on its outer edge)

    asked on May 4, 2016
  12. physics

    A person walks 25 northeast for 3.10km.how far would she have to walk due north and due east to arrive at the same location?

    asked on May 4, 2016
  13. physics

    An archaeologist begins a trip by first walking 30km southeast from the campsite. He stops and sets up a temporal camp for the night. On the second day, he walks 60km in direction 60 degree north of east, at which point he discovers the ancient city of

    asked on May 4, 2016
  14. physics

    The driver of a car slams on the brakes when he sees a tree blocking the road. The car slows uniformly with an acceleration of -5.6m/s for 4.20s marking straight skid marks 62.4m long ending at the tree with what speed does the car strike the tree?

    asked on May 4, 2016
  15. physics

    A Zambian Air Force jet lands with a speed of 100m/s and can accelerate at maximum rate of -5m/s as it comes to rest (a) from the instant the jet touches the runway, what is the minimum time needed before it can come to rest. (b) can the jet land on the

    asked on May 4, 2016
  16. physics

    A fundamental law of motion states that the acceleration of an object is directly proportional to the resultant force exerted on the object and inversely proportional to the mass.if the proportionality constant has no dimensions, determine the dimensions

    asked on May 4, 2016
  17. physics

    show the expression v=at is dimensionally correct where v represents speed an acceleration and t is instant time?

    asked on May 4, 2016
  18. chemistry

    The 4.000g sample of M2S3 is converted to MO2 and loses 0.277g.what is the atomic weight of M?

    asked on May 4, 2016
  19. chemistry

    The active ingredients of an antacid tablet contained only magnesium hydroxide and aluminium hydroxide. Complete neutralization of a sample of the active ingredients required 48.5 ML of 0.187 M hydrochloric acid. The chloride salts from this neutralization

    asked on May 4, 2016
  20. chemistry

    Two different chloride compounds of platinum are known, compound X and Y. When 3.45g of compound X is heated, 2.72g of compound Y is formed to 1.99g of platinum metal and some more chlorine gas. Determine the formulas of compounds X and Y.

    asked on May 4, 2016
  21. chemistry

    A 5.000 gram sanple of dry mixture of potassium hydroxide, potassium carbonate and potassium chloride is reacted with 0.100L of 22.0 degrees Celsius and 740.0 torr,is obtained from this reaction. What was the percentage of potassium carbonate in the

    asked on May 4, 2016
  22. chemistry

    A 2.077g sample of an element which has an atomic mass between 40 and 55 reacts with oxygen to form 3.708g of an oxide. Determine the formula mass of oxide ( and identify the element)

    asked on May 4, 2016
  23. chemistry

    For the reaction below,when the reaction when 0.5000g of X13 reacts completely, 0.2360g of XC13 is obtained. Calculate the atomic weight of element Xmas and identify it 2X13 + 3C12--->2C13+312

    asked on May 4, 2016
  24. chemistry

    0.197g of magnesium is burned in air 2Mg + O2 ---> 2MgO However, some of the magnesium reacts with nitrogen in the air to form Magnesium nitride instead : 3Mg + N2 --->Mg3N2 So you have a mixture of MgO and Mg3N2 weighing 0.315g.Determine what percentage

    asked on May 4, 2016
  25. chemistry

    when the supply of oxygen is limited, iron metal reacts with oxygen to produce a mixture of FeO and Fe203.in a certain experiment, 20.00g of iron metal was reacted with 11.20g of oxygen gas. After the experiment the iron was totally consumed and 3.56g

    asked on May 4, 2016
  26. chemistry

    1. A 12.5843g sample of zrbr4 was dissolved and after several steps all of the combined bromine was precipitated as ArBr. The silver content of AgBr was found to be 13.12160g Assume the atomic masses of silver and bromine to be 107.868 and 79.904.what

    asked on May 4, 2016
  27. chemistry

    A salt contains only barium and one of halides ions. A 0.1480g sample of the salt was dissolved in water and an water and an excess of sulfuric acid was added to form barium sulfate which was filtered, dried and weighed its mass was found to be

    asked on May 4, 2016
  1. chemistry

    Am stuck

    posted on May 5, 2016