Chemistry lab questions

You must show all your work in order to receive full credit for a question.

  1. Identify each of the following pieces of laboratory equipment. (11 pts)

Lab pic 2

Lab pic 1

Lab pic 2

Lab pic 2

  1. Name the three safety items you must wear in the laboratory at all times and two additional safety items located in the laboratory. (5 pts)
  2. Using the data given in the table below, calculate the absolute and relative error, the standard deviation and the coefficient of variation for each mass. (15 pts)

Table1: Standardized mass of weights

Weight of standardized mass (g)Experimental weight of metal (g)

Trial 1

Experimental weight of metal (g)

Trial 2

Experimental weight of metal (g)

Trial 3

10g9.94839.82319.9725
20g19.902319.984219.9990
30g29.976229.985229.9998
  1. To identify a liquid substance, a student determined its density. Using a graduated cylinder, she measured out a 45-mL sample of the substance. She then measured the mass of the sample, finding that it weighed 38.5 g. What is the calculated density of the substance? (8 pts)
  2. An object floats in a 7% solution of NaCl but sinks in distilled water. How does the density of the object compare with the water and with the brine (salt) solution? (8 pts)
  3. Use the differences in the physical properties of BaSO4, K2SO4 and C8H8 (naphthalene) and develop a procedure for separating a mixture containing all three of these compounds. (15 pts)
  4. Find the empirical formula of a compound containing 42.93% carbon and 57.14% oxygen by weight. (15 pts)
  5. Why was water added to the magnesium after its initial burning in experiment # 4? (8 pts)
  6. The chemical formula of blue copper sulfate is CuSO4•5H2O. Determine the mass percent of water in blue copper sulfate. (15 pts)
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