Past Exam 1 Q4

CoCl2 .x -H2O is the purple sample. Calulacte the value for the x integer.   Mass of sample: 1.000 (g)  Mass of water lost: 0.454 (g)

B. Percentage of Water in an Unknown Hydrate CUC2·X H20 UNKNOWN # mass of beaker and watchglass + unknown hydrate (before heating) 123.02 123.02 mass of beaker and watchglass 121.98 122.01 mass of unknown hydrate 122.81 122.78 mass of beaker and watchglass + anhydrous compound (after heating) nass of water (before heating - after heating) Show the calculation for the percentage of water for trial 1 (see Example Exercise 2). Percentage of water in the unknown hydrate Average percentage of water C. Water of Crystallization in an Unknown Hydrate 170.48 g/mol molar mass of anhydrous compound (AC) (see Instructor) percentage of water (see Procedure B) percentage of anhydrous compound (AC) Show the calculation for the water of crystallization (see Example Exercise 3). Water of crystallization НО AC• (Based on how rounding goes at various parts of this, there are two possible answers that I'll consider correct. Just put Formula of hydrate Analysis of Alum 138 down one of them.) 60

Suppose you are hired by the Environmental Protection Agency as an engineer to measure sulfur dioxide (SO2) emissions in a small industrial power plant. And suppose you analyze a gas sample and get the following composition: 75.66% N2, 10.24% CO2, 8.27% H2O, 5.75% O2, and 0.0825% SO2. You show these figures to the factory clerk the next day, and he insists that this analysis is erroneous and states that the fuel is natural gas, contains methane and ethane and does not contain sulfur. You ask if another fuel is used, and sometimes they say they use fuel as fuel, but at the time of analysis they say that this fuel is not used. However, your measurements show that the enterprise is using fuel at the time of measurement, and the responsible person accepts this later and accepts that they have made mistakes.a) Calculate the molar ratio of carbon / hydrogen in the fuel and use the result to prove that the fuel cannot be natural gas.b) Assuming that C, H and S are the elements present in the…

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The hydrated salt, MY3.XH2O, was heated strongly in a crucible to remove all the water molecules of crystallization. The data for this experiment are given in the table below. Mass of empty crucible and cover 28.86 g Mass of crucible, cover, and hydrated salt 32.86 g Mass of crucible, cover, and anhydrous salt 31.24 g Molar mass of anhydrous salt 238.03 g/mol (i) Calculate the % composition by mass of water in the hydrated salt. (ii) Determine the value of x. (iii) M is in Period 4 of the Periodic Table of the Elements. If Y = NO3-, identify the element M. (iv) What is the name of this hydrated salt?

B. TRUE OR FALSE: Read each statement carefully. Write TRUE if the statement is correct and FALSE if the statement is incorrect. 6. It is important to know the chemical formula of compound in order to calculate its percentage composition _7. Percentage composition describes the actual number of atoms of each element in a given compound _8. The percent by mass of a compound can be computed using this formula, (mass of an element per mole/molar mass of compound) x 100 _9. You can use percent composition to get the number of grams in a given compound. 10. Percent composition determine the amount (in percent) of each element present in a compound. C. Solve the given problem. Write your calculations on the provided answer sheet. Paracetamol (C3H,NO2) an organic compound made up of C, H, O and N. It is a common medicine to treat fever and pain because it is an anti-inflammatory drug. Determine the elemental percentage composition of a paracetamol.

H3CO. 'CI AICI3 KMNO4 H20 Br Br AIBR3 AICI,

The formula to use for calculations of dilutions is 1. VịC = V½C2 %3D 2. VịC2 = V½C1 V2 3. a %3D 4. O 1 O 2 O 3 O 4 ||

Balance the chemical equation  C7H14O2+ O2------> CO2+H2O

The hydrated salt, MY3-xH0, was heated strongly in a crucible to remove all the water molecules of crystallization. The data for this experiment are given in the table below. Mass of empty crucible and cover Mass of crucible, cover, and hydrated salt 30.29 g 35.57 g Mass of crucible, cover, and anhydrous salt 34.57 g Molar mass of anhydrous salt 230.99 gimol O Calculate the % composition by mass of water in the hydrated salt O Determine the value of x.

1)A solution of Na2CO3 is prepared by dissolving 0.511 g of the solid in approximately 30 mL of water.  How many moles of Na2CO3 does this solution contain?Express your answer to the correct number of significant figures.  2)Suppose the Na2CO3  solution described in Question 1 is added to a solution that contains excess CaCl2?  What is the maximum number of moles of solid CaCO3 that can form in the resulting precipitation reaction?

6. A student reported the following percentages for his unknown mixture: 25% NH4CI, 30% NaCl, and 50% SiO2. Assuming that the calculations were done correctly, provide a plausible explanation for the students results.

Balance the equation ClO3^- + I^- —> I2 + Cl^-

Balance the following chemical equation CB₂H.(g) + O₂(g) > CO₂(g) + H₂O(g)

I'd just like to know if question 3c's answer is correct, please and thank you.

balance the equations below