Chem Lab 2

Suppose a student measured the mass of a sample that has a known mass of 40.5809 g using an analytical balance. The mass they observed was unstable, constantly jumping between 39.5 and 41.5. Choose all of the following reasons that could cause this error. O The doors to the analytical balance were not closed completely, allowing an air current to circulate inside the balance. One weigh boat was used to tare the balance while a different one was used when the sample was massed. Twice the amount of sample was placed on the analytical balance. O The sample was heated, causing a convective flow.

7. 22 This question is about several salts. (a) A hydrated salt, compound A, is analysed and has the following percentage composition by mass: Cr, 19.51%; CI, 39.96%; H, 4.51%; O, 36.02%. Calculate the formula of compound A, showing clearly the water of crystallisation. Show your working. formula of compound A = (b) A student carries out an experiment to determine the amount of water of crystallisation in the formula of another hydrated salt. The student intends to remove the water by heating the hydrated salt. A diagram of the apparatus used by the student is shown below. crucible pipeclay triangie The student adds the hydrated salt to the crucible and weighs the crucible and contents. The student heats the crucible and contents and allows them to cool. The student weighs the crucible and residue. The student's results are shown below. 16,84 Mass of crucible + hydrated salt/g 16.26 Mass of crucible + residue after heating/g

1) State your interpretation of the meaning of the slope for the first graph you prepared of Volume of Steel Nuts (mL) versus Number of Steel Nuts. Hint: Understanding the meaning of a slope involves several factors: the units which are a ratio of the y axis units over the x axis units, the interpretation of the slope as “number of the y axis units for every one of the x axis units” and the concept that constructing the best line or curve that follows the trend in the data is a sort of averaging of the random error throughout the data.

42.How many of the following should be included in a good hypothesis? (i) A prediction of the results of the experiment (ii) A step-by-step walkthrough of how to do the experiment with specific references to amounts of reactants, glassware used, and other experimental details (iii) A summation of the data collected after doing the experiment, with comments on accuracy and precision if possible. (iv) A detailed list of chemicals that will be used (v) Waste disposal procedures (vi) A brief scientific explanation of the predicted results. Said another way, the hypothesis should include a scientific explanation of why the predicted results are expected.   A. 1   B. 2   C. 3   D. 4   E. 5

Simplify the following quantities using a unit with an appropriate prefix: (a) 2.5 104 Hz. (b) 8.43 105 mmol. (c) 7.44 104 nm. Show complete solution

Classify the following as qualitative or quantitativestatements, giving your reasons. (a) The sun isapproximately 93 million mi from Earth. (b) Leonardoda Vinci was a better painter than Michelangelo. (c) Iceis less dense than water. (d) Butter tastes better thanmargarine. (e) A stitch in time saves nine.

An electric current of 0.650 A flows for 1.0 second. Calculate the amount of electric, charge transported.. Be sure your answer has the correct unit symbol and 2 significant digits. 0 x10 ロ・ロ X μ = 5.:.

1. A piece of metal was weighed on a laboratory balance five times and gave the following values: 15.75, 15.73, 15.77, 15.76and 15.74 grams.Determine the average mass andstandard deviation from the mean mass.(b) An object weighs 0.0930 gramson an analyticalbalance. Indicate theaccuracy of the balance and the number of significant figures in this weight.

The pharmacist attempts to weigh 0.375 g o morphine sulfate on a balance of dubious accuracy. When checked on a highly accurate balance, the weight is found to be 0.400 g. Calculate the percentage of error in the first weighing.

Whilst working in the pharmacy aseptic unit you are asked to prepare 5 litres of a solution containing potassium ions 1 mmol/mL. What weight of potassium chloride is required? (atomic weight of potassium = 39: atomic weight of chlorine = 35.5) Units - g

Please don't providehandwrittin solution...

Richards and Williard determined the molar mass of lithium and collected the following data  (a) Find the mean molar mass determined by these workers.  (b) Find the median molar mass (c) Assuming that the currently accepted value for the molar mass of lithium is the true value, calculate the absolute error and the present relative error of the mean value determined by Richards and Williard.  (f) What factors have led to changes in molar mass since 191?  (g) How would you determine the accuracy of a molar mass?   Experiment  Molar mass, g/mol 1 6.9391 2 6.9407 3 6.9409 4 6.9399 5 6.9407 6 6. 9391 7 6. 9406

In the year 2013, an estimated amount of 36 billion metrictons (1 metric ton = 1000 kg) of carbon dioxide 1CO22 wasemitted worldwide due to fossil fuel combustion and cementproduction. Express this mass of CO2 in grams without exponentialnotation, using an appropriate metric prefix

11 of 11 I Review | Constants Periodic Table Suppose that you want to find the equation for a line that passes through the two points (0,3) and (4, 9). What is the slope of this line? Express your answer numerically. > View Available Hint(s) Πνα ΑΣΦ ? m = Submit rt C Complete previous part(s) 9:41 PM 36%

How many significant figures are shown in each ofthe following? If this is indeterminate, explain why.(a) 450; (b) 98.6; (c) 0.0033; (d) 902.10; (e) 0.02173;(f) 7000; (g) 7.02; (h) 67,000,000

Earth's oceans have an average depth of 3800 m, a total area of 3.63 x 10 km², and an average concentration of dissolved gold of 5.8 × 10. If a recent $987.00 troy oz what is the value of gold in the oceans? (I troy oz 31.1 g) Round your answer to 2 significant figures. Note: Reference the SI prefixes and Unit conversions for derived SI units tables for additional information. price of gold was 0

What is number 5?

Report all numerical answers to the correct number of significant figures! (a) Give the names of the following elements: (i) Ag (ii) V (b) Give the symbols of the following elements: (i) aluminum (ii) copper 1. 2. Report the answers of these calculations to the correct number of significant figures: (a) 3.7793 x 8.324 x 7.4976 = ? (b) 10.4071 +66.1441 +12.515 = ? (c) (7.971 x 10¹7) (3.75 x 10³)/7.8416 = ? (Report answer in exponential notation.)

A chemist prepares a solution of copper(II) fluoride (CuF;) by measuring out 1.31 mg of copper(11) fluoride into a 50 mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in mol/1. of the chemist's copper(II) fluoride solution. Be sure your answer has the correct number of significant digits. moll. OP

Perform the calculation and record the answer with the correct number of significant figures. (34.123+1.20)/(98.7654−7.384)          Needs Complete typed solution with 100 % accuracy.    Handwritten solution is completely prohibited.