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Each student is given an individual sample bottle containing ml of hydrochloric acid with an unknown concentration

 
 

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1.AP Chem AB FRQ Question 1 A sample consisting of 50. mL of 0.400 M solution of the acid, HClO4, is titrated ...

titrated with a 0.200 M solution of the base, LiOH. Write the balanced chemical reaction for neutralization reaction: HClO4 (aq) + LiOH (aq) → LiClO4 (aq) + H2O (l) Write the NET ionic equation for the neutralization reaction. OH⁻ (aq) + H⁺ (aq) → H2O (l) Compute the pH of the titration solution. Show your work i) before any of the base is added ii) after 25. mL of base is added iii) after 50. mL of base is added A student performs the titration with the same chemicals but with smaller volumes of each chemical . Which of the following titration curves could represent the titration. Explain A because this entails a strong acid and a strong base. Question 2 A student performs a titration of an unknown acid with a strong base and gets the following titration curve: a) The student consults the list of pKa of acids shown below. If the acid is listed in the table below, which is the most likely identity of the unknown acid? Explain. Acid Ka HF 7.2 x 10-4 CH3COOH 1.8 x 10-5 H2CO3 4.3 x 10-7 HBrO 2.0 x 10-9 The unknown acid is HBrO because the calculated Ka is in between 50^-4 and 50^-6 and 2.0 x 10^-9 lies in between them. b) What is the initial molarity of the acid? 10^-3 = 0.001M Question 3 a) Describe the components and the composition of an effective buffer solution. Explain how the components of the buffer allow the buffer to maintain its pH. An effective buffer solution has a weak acid and its conjugate base or a weak base and its conjugate acid. A buffer solution is most effective when the ratio of its component concentrations is close to 1, also when the pH is equal to the pka of the acid.; The components of the buffer allow the buffer to maintain its pH because buffers can absorb excess H+ions or OH– ions. An employer is interviewing four applicants for a job as a laboratory technician and asks each how to prepare a buffer solution with a pH of 5.0. The following constants may be helpful: hydrazoic acid, pKa = 4.74 Boric acid, pKa = 9.23 Archita A. says she would mix equal molar solutions of hydrazoic (HN3) and sodium azide (NaN3) solutions. Bradley B. says she would mix equimolar Boric acid (H3BO3) and HCl solutions. Carlos C. says he would mix equimolar Boric Acid (H3BO3) and sodium dihydrogen borate (NaH2BO3) solutions. Delia D. says he would mix equimolar hydrazoic Acid (HN3) and NaOH solutions. b) Which of these applicants has given an appropriate procedure? Explain your answer Delia because she is using Sodium hydroxide which results in a pH of 5. NaOH is a strong base and in order to have an effective buffer a weak acid must be incorporated which is the HN3. c) Explain what is wrong with the erroneous procedures. The rest all incorporate a strong acid and a strong base or a weak acid and a weak base which don’ result in an effective buffer. d) The applicants have access to the 1 Liter volumes of each of the solutions listed above. They have access to graduated cylinders. In order to make 1.0 Liter of the correct 5.0 buffer solution, what volumes of the two chemicals must be mixed?
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2.Each student is given an individual sample bottle containing 200 mL of hydrochloric acid with an unknown concentration. ...

nknown concentration. Use titration with 0.1500 M NaOH (aq) to determine the concentration (molarity) of the HCl (aq). Hint: use 25.00 mL of acid for each titration.
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3.dehydrated cobalt (ii) chloride Be sure to include subheadings (see bold text below) formulas, and units. Chemical Equation: Write a generic ...

units. Chemical Equation: Write a generic chemical equation for the dehydration of cobalt (II) chloride ∙ x hydrate (include the state symbols of the reactant and two products). [T2] Mass of Reactants and Products: a) Calculate the initial mass of the hydrated cobalt (II) chloride. [T1] b) Calculate the final mass of the anhydrous cobalt (II) chloride remaining in the cruiio8icible. [T1] c) Calculate the mass of water given off by the sample of hydrated cobalt (II) chloride. [T1] Moles of Products: a) Calculate the moles of anhydrous cobalt (II) chloride remaining in the crucible. [T1] b) Calculate the moles of water released from the hydrate. {T1] 4. Mole Ratio a) Create an experimental mole ratio between the b) and a). [T1] 5. Formula of Hydrate: State the chemical formula you have determined for this hydrate. Round the formula to the closest whole number value for x. [T1] Discussion/Conclusion Questions: [T6] Based on the chemical formula of the hydrate, calculate the percentage composition (percent by mass) of the hydrated cobalt (II) chloride. Remember to determine the percentage of each element (Co, Cl, H, and O). [T2] A possible source of systematic error in this experiment is insufficient heating. Suppose that the hydrate was not completely converted to the anhydrous form. Describe how this would affect: the calculated percent by mass of water and the experimental molecular formula (i.e. would x be higher, lower or the same). Suppose a student spilled some of the hydrated cobalt (II) chloride. Describe how this would affect the calculated percent by mass of water (would it be higher, lower or the same) and the experimental chemical formula of the hydrate. [T2]
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4.How to calculate the probability of "A" given multiple other events? Example, let's say i have a deck of 10 ...

k of 10 cards numbered 1-10. I draw 5 cards (each time i draw i put the card back and shuffle). The numbers were 8, 2, 4, 9, and 4. What is the probability that it will be 4 on the 6th time i draw? I know each card has a 10% chance of being drawn. I also know the probability of a 10% event happening twice is 1%. But wouldnt the odds be lower since i drew 4 a couple trials earlier? How exactly would i calculate that. If there is an online calculator that executes the answer id like to know. Just a college student who craves probability. :)
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5. Value: 1 equation image indicator a. (x - 2)2(x - 3)2 b. (x2+ 4)(x2+ 9) c. (x - 2)(x + ...

2)(x - 3)(x + 3) d. (x2 - 4)(x2+ 9) Value: 1 The table below shows the cost of purchasing a standard stapler at five office supply stores, A through E. If the median cost of purchasing a standard stapler for these stores was $17.99, which of the following could NOT have been the cost of the stapler for Store A? staplergraph.jpg a. $19.95 b. $18.95 c. $16.95 d. $19.25 Value: 1 If equation image indicator then x = a. 7 b. 1/5 c. 5 d. 1/7 Value: 1 A six−sided die, with sides numbered 1,2, 3,4,5, and 6, is tossed. What is the probability of tossing a number less than three? a. 1/3 b. 0 c. 1/2 d. 1/4 Value: 1 If 6m + 4 = 8m, then 4m = a. 6 b. 2 c. 8 d. 4 Value: 1 In the xy-plane, what is the y-intercept of the graph of the equation equation image indicator? a. 2 b. 4 c. 16 d. There is no y-intercept. Value: 1 Which of the following equations has both 2 and −4 as solutions? a. x2 + 6x + 8 = 0 b. x2 - 2x - 8 = 0 c. x2 + 2x - 8 = 0 d. x2 - 2x + 8 = 0 Value: 1 The perimeter of a square is 20 ft. If you increase the length of the square by 2 feet and decrease the width by 1 foot, what is the area, in square feet, of the new figure? a. 22 b. 28 c. 35 d. 40 Value: 1 (3x-2y4)-3 = a. equation image indicator b. equation image indicator c. equation image indicator d. equation image indicator Value: 1 A softball is tossed into the air upward from a first floor balcony. The distance of the ball above the ground at any time is given by the function, distance function.png, where h(t) is the height of the softball above the ground (in feet) and t is the time (in seconds). What was the maximum height, in feet, of the softball above the ground after it was thrown? a. 28 b. 30 c. 32 d. 34 Value: 1 A group of 100 people, some students and some faculty, attended a museum opening. Each student paid $10 per person for entrance to the museum and each of the faculty paid $25 per person for entrance. If the total paid, for all 100 people, was $1300, how many students attended the museum opening? a. 20 b. 50 c. 70 d. 80 Value: 1 The ratio of Sam's age to Hank's age is 5 to 3. If the sum of their ages is 24, how old is Hank? a. 21 b. 15 c. 19 d. 9 Value: 1 In the xy−coordinate plane shown below, point P has coordinates (8, −6). Which of the following is an equation of the line that contains points O and P? O and P graph.jpg a. equation image indicator b. equation image indicator c. equation image indicator d. equation image indicator Value: 1 The variables x and y are inversely proportional, and y = 2 when x = 3. What is the value of y when x = 9? a. 54 b. 6 c. 2/3 d. 3/2 Value: 1 A farmer has 1235 trees to be planted on a rectangular parcel of land. If there are 24 trees planted in each row and each row must be complete before it is planted, how many trees will be left over after planting? a. 21 b. 11 c. 0 d. 55
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1.AU MAT 120 Systems of Linear Equations and Inequalities Discussion

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