333 lecture

How is accuracy and precision related to errors incurred in the chemical analysis? Why systematic errors are also called determinate errors? Why random errors are also called indeterminate errors? Give two examples of each of the following sources of errors.             a. Instrumental error             b. Personal error             c. Method/operational error

3. A method of analysis yields masses of gold that are low by 0.4 mg. Calculate the percent relative error caused by this result if the mass of gold in the sample is a. 500 mg​​ b. 250 mg c. 60 mg 4. The method described above is to be used for the analysis of ores that assay about 1.2% gold. What minimum sample mass should be taken if the relative error resulting from a 0.4-mg loss is not to exceed a. -0.1% b. -0.8%

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

4. (Also can you explain what is meant by determinant error)

Suppose you prepared a plot for this experiment and the equation of the trendline was y = 78.012x+0.01251  Based on this information, what would be the absorbance of the solution if the concentration is 0.009697 M? DO NOT include units in your answer.   Follow sig. fig. rules as you perform your calculations, but DO NOT round your answer until the very end of your calculation.  Credit will only be given for answers that have the correct value and significant figures.

What are replicates in Analytical Chemistry? O The component of a sample that repeats over different assays. Similar assays done to different samples A sample that contains exactly the same amount of analytes than the original sample similar samples that are analyzed at the same time and in the same way

What does the phrase 'fit for purpose' mean in relation to analytical chemistry? Please provide examples too.

In analytical chemistry, what is a standard method? Include any sources you used to answer this question. Give an example of a standard method, and the reference for it. 2.

tributi X Normal Distributi X ample Work rmat Tools Extensions Help locument/d/1KWoB0hrXolu7UEKbq4f8LBMHfpjHBRVU3qUzVI7K80U/edit Saved to Drive Normal text I 2022-2023 Mr. R X - I ▼ | Calibri 1 16 11. Which quantity is used to define 1 atomic mass unit? 3 100 Copy of Chern B x I UA 4 5 hp 4/27 - Unit 5.mp4 X particles. 12. How many molecules are there in 2 g of water (H₂O)? HINT: Molar mass of water is 18 g/mol Pathway: mass → moles → molecules E Did You Know? The word mole represents a specific number of objects, 6.022 × 10²¹ , just as the word dozen represents a specific number of objects, 12. The molar mass is the mass of a substance that contains 6.022 × 10²¹ DC Normal DE VE E 127 64°F Mos

4. Experimental Procedure. a. How many (total) data plots are to be completed for this experiment? Account for each. b. What information is to be extracted from each data plot?

The mass of magnesium used in this experiment is critical to determining the moles of hydrogen gas generated. The analytical balances used in Chemistry 1A labs are very sensitive to point that touching materials with your fingers before measuring them can affect the measurements. The balances are sensitive enough to detect dirt and oils from your fingers transferred to the magnesium. Would your experimental value of R increase or decrease if the mass of magnesium measured was artificially high due the touching it with your hands? Increase Decrease

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Which scale is most useful for reporting data from the spectrometer? Why?

? 1. 03 2. DMS Br₂, DCM KMnO4, Hot ? X2

Explain your rationale for using the summative assessment (below) from the lesson plan on mixing substances in a 5th-grade classroom based on the below standard and learning objective, including how it aligns with the learning objective.  Summative Assessment  Summative: Components of the Lab Report Purpose: The student should clearly state the purpose of the experiment, which is to determine whether the mixing of two or more substances results in new substances. Procedure: The student should describe the steps they took to conduct the experiment. This includes the substances they chose to mix and the safety equipment they used. Observations: The student should record any observable changes that occurred when the substances were mixed. This could include a color change, the formation of a precipitate, or a change in temperature. Conclusion: The student should state whether a new substance was formed based on their observations. They should also reflect on their accuracy in…

Average and Uncertainty The molar mass of an unknown compound was determined in three repeat experiments. The molar masses obtained were 82.23, 81.55 and 82.00 g/mol. Assume the uncertainty in the average value to be the half range. Enter the average value and its uncertainty, both rounded to the appropriate number of digits (according to the Rules outlined in the Chem121 Lab Manual Appendix). g/mol

An oceanographer creates a model of a wave tank with a sand table to simulate beach erosion. What type of model is being used? 7 O statistical model O mathematical model O conceptual model O physical model