Let's say you are working in a laboratory with a group and you are the only student who has taken chemistry courses. Your laboratory received a sample of cobalt(II) chloride which has the formula CoCl2·xH2O. Let's say your boss asked you to find the formula of this hydrate salt sample since you are the only chemist there. From your laboratory experience, simply explain the experimental procedure you would follow to find the formula of this unknown sample. Then, use the given data for the calculation part.  Mass of crucible: 32.27g Mass of crucible + unknown hydrate: 33.92 g Color of unknown hydrate: purple Mass of crucible + anhydrous form of hydrate: 33.41 g Color of anhydrous form: sky blue

Pick an element from the Periodic Table AFTER number 25, Mn, and do not pick a diatomic element.  Pick something different and fun! Now answer the following questions on a piece of paper which you will upload as a pdf file, and show all your work with units for calculations for any credit. Use your CHM 130 Periodic Table for molar masses and use 6.02 x 1023 for Avogadro's number or you may be counted wrong!!! 1. What is the symbol for your element? (Must be after Mn in Periodic Table) 2. What is the molar mass of your element? (include units) 3. How many atoms are in a mole of your element? (No calculation needed) 4. If you had 14.5 grams of your element, how many moles is that? 5. If you had 14.5 grams of your element, how many atoms is that? 6. Theoretically speaking, if your element was in the gas state at STP, how many grams is 2.25 liters of your element? (Most elements are not gases at STP so this question is just theoretical) You may not use the Ideal Gas Law to solve this.

Cobalt, a transition metal, forms both the Co2+and Co3+ions. Write the correct formulas and give the name for the oxides formed by the two different ions.

There are 1.699 x 1022 atoms in 1.000 g of chlorine.  Assume that chlorine atoms are spheres of radius 0.099 nm and that they are lined up side by side in a 0.50 g sample.  How many miles in length is the line of chlorine atoms in the sample? 1 mi = 1609 m

You analyzed 3.725 g of an unknown mixture of NaCI, SiO2, and CaCO3. You isolated 1.108 g NaCl, 0.848 g SiO2, and 2.033 g CaCO3. Your TA later informs you that the original mixture was 25% NaCl, 25% SiO2, and 50% CaCO3. Choose a possible explanation for the discrepancy between your values and the actual percentages. O The CACO3 was decanted into the SIO2 O NaCl was not completely dried before its mass was determined. O The SiO2 solution was cooled to room temperature and then weighed. O CaCl2 is a desiccant and therefore absorbed water before K2CO3 was added. O CaCO3 did not completely react with HCI. As a result, less CaC12 was produced O CaCO3 is slightly soluble in water. Some of the CaCO3 dissolved during the NaCl isolation step.

There are two gas compounds that are made out of element  A and B. This is the mass percentage of the two compounds. Compound 1: 30.43% A, 69.57% B Compound 2: 63.64% A, 36.36% B In a normal state element A and B exist as a gas. (It can be mono atomic molecule, diatomic molecule or triatomic molecule) When you react gas A and gas B and make a product these things come out. (All in same temperature and pressure) 1 Volume of Gas A + 2 Volume of Gas B = 2 Volume of Compound 1 2 Volume of Gas A + 1 Volume of Gas B = 2 Volume of Compound 2 Determine the relative mass of element A and B from the reaction formula above. Also you should assume the simplest chemical formula of reactant and products

Two experiments were conducted: 1.2.750 g of copper(II) oxide, CuO2, was reduced by heating at high pressure with excess hydrogen to yield 2.196 g of copper Cu. 2. 1.179 g of copper Cu was dissolved in nitric acid to yield copper(II) nitrate, which was converted to 1.476 g copper(II) oxide, CuO2, on ignition. Show that the results illustrate the law of definite proportions by calculating the percentage of oxygen in copper(II) oxide in experiments 1 and 2. Express your answers numerically to two decimal places, separated by commas. Do not enter the percent symbol. ▾ View Available Hint(s) Percentage of oxygen in sample 1, sample 2 = copper oxide in the sample 15. ΑΣΦ the second experiment S ?

Hydrated substances contain H2O as part of their formulas. When a hydrated substance is heated, water is driven off and an anhydrous (without water) substance is formed. In this experiment: determine the formula of 2 different hydrates: A copper (II) sulfate hydrate and a zinc sulfate hydrate 1) Why did the color of the cobalt (II) chloride change? 2) What would you expect to happen to the color of the anhydrous (without water) sample if it was removed from the heat and left in an open container in the lab? 3) One way to tell if all of the water has been removed for this compound is to wait until the color stops changing, but not all hydrates change color when they are dehydrated. What would be another way to tell if all of the water has been removed from a sample?

Locate each of the following elements in the periodic table;give its name and atomic number, and indicate whether it isa metal, metalloid, or nonmetal: (a) Li, (b) Sc, (c) Ge, (d) Yb,(e) Mn, (f) Sb, (g) Xe.

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