Question

# 7) Suppose your crystal's density is 2.312 g/cm3. Use conversion factors to convert this to mg/μl...

7) Suppose your crystal's density is 2.312 g/cm3. Use conversion factors to convert this to mg/μl Show all your work and all your units throughout. Now to the doctor's office: 8) I have come to see you, the doctor, because I was feeling a bit ill. The first thing the nurse did was look at me and see I had a large growth in my neck. “Wow!” she said. “How long has this been going on?” “For a couple of months”, I replied. After going through a bunch of tests, I was diagnosed with a goiter. This problem was historically treated with seaweed and is caused by a deficiency of iodine in the diet. The doctor prescribes iodine tablets. You, as the nurse, are faced with deciding which bottle of iodine I need. The doctor says I need Iodine-127. The supply person has made a mistake and put two different types of iodine on the shelf. I need Iodine-127. This is the heavier isotope of Iodine, the other being Iodine -126. a) Iodine is a diatomic element. Therefore, how would you represent elemental iodine in a chemical equation? Explain why you think it occurs in this way? b) Iodine-126 and Iodine-127 are isotopes of each other. Explain, in your own words, what an isotope is and write the complete chemical symbol for Iodine-126 and Iodine-127 and label what each number means. (this link will teach you how to write isotopic notation in word) c) What element do you think must have been present in seaweed to be a traditional therapy? ____________ Now to the hospital? 11) I have checked into the hospital because I was feeling pretty sick and jittery. The first thing you did was ask me what I had done last night. “I went out with a couple of friends to a Chinese restaurant” I said. “Did you eat or drink anything strange?” you ask. “Just one cup of Chinese tea, and of course I have a one cup sample of it right here” You decided to send this one cup sample to the lab to have it analyzed. Below is the report sheet: Report: The tea was found to contain a large amount of the substance whose percent composition is given below: mass isolated from the cup: 1.53 grams percent composition: 49.49 % C; 6.48 % O; 5.19 % H; 28.86% N Molar Mass of compound; 194.16 g/mol a) From the information in the report, determine the empirical and molecular formula. Show all work. b) I am a chemistry teacher, and I ask you how many moles of the mysterious substance I ingested so I can tell my students. What would be your answer? c) I am also an extremely irritating patient, and I ask you how many molecules of this substance were in the tea sample. What would be your answer? 12) I have showed up at the hospital again. You are looking forward to hearing my new story! I have decided to take a new kind of baking soda, CaCO3 to control my blood pH. It reacts in my stomach, according to the following equation, and I feel bloated! ____ CaCO3(s) + ____HCl(aq) →_____H2O(l ) + ____CO2(g) + ___CaCl2(aq) a) Balance this equation by inserting the correct coefficients in red(even if they are the number one)in front of each reactant and product. b) You know from your physiology courses that I have 0.50 moles of hydrochloric acid in my stomach. I tell you I took 15 grams of the new baking soda. Calculate how many moles of carbon dioxide each reactant will make, then decide which compound will limit the amount of carbon dioxide produced. Show your work to back up your answer. c) Based upon your answer from part b) above, how many grams of carbon dioxide could have been made in my belly? d) You told me to burp into a bag and I will feel better. I ended up burping 5.86 grams of carbon dioxide. This is how much carbon dioxide was actually made in my belly. What is the percent yield for the above reaction? Show all work.

#### Homework Answers

Answer #1

Sol:-

1 g = 1000 mg

1 cm3 = 1000 microlitre = 1000 μl

So

1 g/cm3 =   1000 mg / 1000 μl = 1 mg / μl

i.e 1 g/cm3 = 1 mg/μl

therefore

Crystal's density = 2.312 g/cm3 = 2.312 mg/μl

8.(a)

Representation of elemental iodine in a chemical equation is = I2

Explanation :- In order to complete its octet ( i.e 8 electrons per iodine atom by sharing their one electron ) iodine exist as I2 molecule at room temperature.

(b)

Representation of I-127 is = 53 I127

Representation of I-126 is =  53 I126

Explanation :-

Representation of element ( say element 'X') with atomic number 'Z' and mass number 'M' = ZXA

(c)

Element must have been present in seaweed is Iodine (I) .

Explantion :-

Seaweeds contains 0.5% by mass of I- .

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