What is the pH of 25 ml of 0.100 M ammonia sln. 1) before titration begins ; 2) after 12.50 ml of 0.100 M HCL is added; 3) after 14 ml of 0.100 M HCL is added; 4) after 25 ml of the HCL is added; and 5) after 35 ml of the HCl is added. pkb of ammonia = 4.74

Calculate the pH for each of the following cases in the titration of 25.0 mL of 0.230A pyridine, C5H5N(aq) with 0.230M HBr(aq):

a.) before addition of any HBr

b.) after addition of 12.5 mL of HBr

c.) after addition of 20.0 mL of HBr

d.) after addition of 25.0 mL of HBr

e.) after addition of 36.0 mL of HBr

Mr. Wong buys gold from gold mines and resells it in the retail market in Country A. Before the gold is sold in the retail market, Mr. Wong needs to store the gold in a warehouse and the storage cost is $10 per kg of gold per day. For examples, if Mr. Wong buys 1kg of gold on 22 April 2020 and sells it on the same day, Mr. Wong has to pay a storage cost of $10. If Mr. Wong buys 1kg of gold on 22 April 2020 and sells it on the next day, Mr. Wong has to pay a storage cost of $10 x 2 = $20. There is no fixed cost in Mr. Wong’s gold business.

Mr. Wong is the sole retailer of gold in Country A and he would like to maximize the profit of his business.

The market demand for gold is Q^d = 3000-75P and

The corresponding marginal revenue is MR = 40 – 2Q/75,

where Q^d is the quantity demanded for gold (kg/day) and P is the price of gold per kg.

For instance, when P = 20, Q^d = 3000-75(20) = 1500 and MR = 40-2(1500)/75 = 0.

(i) Suppose that Mr. Wong buys gold at a price of $10 per kg. What should be the price of gold set by Mr. Wong in the retail market and what is the quantity of gold sold in the retail market? What is the profit of Mr. Wong’s business?      

(ii) Suppose that the government of Country A requires Mr. Wong to pay for a licensing fee for operating his gold business. After paying for a licensing fee of $2,000 per day, Mr. Wong can sell whatever amount of gold in the retail market in Country A. Briefly discuss how this licensing fee may affect your answers in (i).

(iii) Now, Mr. Wong does not need to pay any licensing fee. Yet, because of a logistical problem, gold purchased today can only be sold on the next day. Briefly discuss how this logistical problem will affect your answers in (i).   

(iv) Now, Mr. Wong does not need to pay any license fee and there is no logistical problem. On 22 April 2020, after Mr. Wong purchased 750kg of gold at a price of $10/kg, the government of Country A announced that the people of Country A cannot buy gold anymore. On the same day, a foreign businessman contacted Mr. Wong suggesting to buy 750kg of gold from him at a price of -$5 (minus $5 per kg). This is the only offer to Mr. Wong on that day. If you were Mr. Wong, will you accept this offer and sell your gold at a negative price?  

(v) “A futures contract for U.S. crude (oil) prices dropped more than 100% and turned negative for the first time in history on Monday, showing just how much demand has collapsed due to the coronavirus pandemic (CNBC April 19, 2020)”. With reference to your answer in (iv), briefly explain why crude oil price could be negative.

The following data are from a repeated-measures study examining the effect of a treatment by measuring a group of n=5 participants before and after they receive the treatment.

A.) calculate the difference scores and MD

B.) compute SS, sample variance, and estimated standard error.

C.) is there a significant treatment effect? Use Alpha=0.05

Participant Before Treatment After Treatment
A 8 7
B 7 5
C 6 6
D 7 6
E 9 7

1) A buffer solution contains 0.447 M NaH₂PO₄ and 0.325 M Na₂HPO₄. Determine the pH change when 0.117 mol NaOH is added to 1.00 L of the buffer.

pH after addition − pH before addition = pH change =_____

2) A buffer solution contains 0.455 M NH₄Br and 0.243 M NH₃ (ammonia). Determine the pH change when 0.056 mol NaOH is added to 1.00 L of the buffer.

pH after addition − pH before addition = pH change = _____

A coach uses a new technique in training middle distance runners. The times for 9 randomly selected, independent athletes to run 800 meters before and after this training are shown below. Assume the distribution of differences are normally distributed

Before 115.2 120.9 108.0 112.4 107.5 119.1 121.3 110.8 122.3

After 116.0 119.1 105.1 111.9 109.1 115.1 118.5 110.7 120.9

Build and Interpret 90% confidence interval for the true mean difference in 800-meter times.

Question #4
A coach uses a new technique to train gymnasts. 7 gymnasts were randomly selected and their competition scores were recorded before and after the training. The results are shown below.

Using a 0.10 level of significance and Critical Value method to test the claim that the training technique is effective in raising the gymnasts' scores. (Mean difference is less than zero)

A coach uses a new technique to train gymnasts. 7 gymnasts were randomly selected and their competition scores were recorded before and after the training. The results are shown below. Use a 0.01 significance level to test the claim that the training technique is effective in rising the gymnasts’ scores.

We are interested to see whether the level of the minimum wage affects employment. In order to study this issue they got data from a random sample of 330 California fast food restaurants before and after an increase in the Californian minimum wage from $3.30 to $4.10 per hour. The change in full time equivalent employees per restaurant in the sample before and after the increase was 0.8 with a variance of 77.5.

Test whether this suggests the increase in the minimum wage had an effect on employment.