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.

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

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.:.

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.

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

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

EXPLAIN YOUR ANSWER THOROUGHLY!

What is number 5?

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.     1     2     3     4     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.)

Part C F10 BO O 3.04 × 10³ 6.27 x 10-1 The dosage of quinine when a 145-lb adult takes a 200.-mg tablet is equivalent to ug drug per kg of body weight. ► View Available Hint(s) O 627 O 1.38 × 10³ P Pearson * Education Inc. All rights reserved. | Terms of Use Privacy Policy. Permissions Contact Us | Bb Home L End Insert ■ Review |- Constants | Periodic Table 1 2

Dimensional Analysis is a way of doing numerical "book-keeping" when converting quantities or performing calculations. • When converting quantities from one unit to another, conversion factors are used. Solving with Dimensional Analysis and Multiple Units: If I am in Canada where the price of gas is $1.022 USD·L1, how much will it cost me to fill up my gas tank if I travelled 125 km? • Let's also assume that my car gets an average of 30.0 miles/gallon.

How many of the following should be included in a good hypothesis? (1) 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 (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. (v) Waste disposal procedures 0 1 O 2 O 3 0 4 0 5

Suppose that instead of using the cylindrical rod of Example 1-2 to prepare a 1.000 kgmass we were to use a solid spherical ball of copper What must be the radius of this ball?

A student performed an analysis of a sample for its calcium content andgot the following results:                              14.92%             14.91%              14.88%        14.91%The actual amount of calcium in the .sample is 15.70%. What conclusions can you draw about the accuracy and precision of these results?

Wrong (L) - calculator- Google Search d/1PrqdNDx-hBYyzKo-xfiM9-Jlq7EAaWe3GBt t3U3jDo/edit Calculator O A Land of Permane... t edit was seconds ago I U A 三| 扫 E▼ 三▼ 4 Fe + 30, - 2 Fe,0, 4. What volume (liters) of O, is required to react with 1.7 moles of Fe? 1.7 moles Fe 1 mole O. 224 LO, 4 moles Fe 1 mole O. * How many meles of iron would have to reacr to produce 35moles of tron ) oxide"

A chemist must dilute 52.5 mL of 323. mM aqueous silver perchlorate (AgCio,) solution until the concentration falls to 8.00 mM . He'll do this by adding distilled water to the solution until it reaches a certain final volume. Calculate this final volume, in liters. Be sure your answer has the correct number of significant digits. alo

1) Perform the indicated mathematical operations. State the uncertainty of the final answer as ± 1-digit variation in the least significant digit. (remember that the last significant digit's place holder is the most uncertain digit!) 7.700 x 2.1 = uncertainty: 2.132 + 17 + 4.04 = uncertainty: 27000 + 500 = uncertainty: 30.0 x 50.0 = uncertainty: (9.6 × 107)(1.24 × 10³)_ uncertainty: 1.897 x 102

A chemist must dilute 33.3 mL of 592. mM aqueous barium chlorate (Ba(ClO,) ) solution until the concentration falls to 454. mM . He'll do this by adding distilled water to the solution until it reaches a certain final volume. Calculate this final volume, in milliliters. Round your answer to 3 significant digits.