What is the pH of a buffer that is prepared by mixing 30.0 mL of 1.0 M HF and 20.0 mL of 2.0 M KF? (Ka for HF 7.2 x 10−4)

What is the pH of a solution that contains 0.40 M CH3COOH and 0.30 M CH3COONa at 25°C (Ka=1.8 x 10−5)?

What is the pH of a buffer that is prepared by mixing 30.0 mL of 1.0 M HF and 20.0 mL of 2.0 M KF? (K a a for HF 7.2 x 10 −4 )

PART A: Calculate the ∆G for a cell composed of a Zn electrode in a 1.0 M Zn(NO3)3 solution and an Al electrode in a 0.1 M Al(NO3)3 solution at 298 K.

​PART B: Write the net ionic equation describing the reaction occurring spontaneously in the cell described in PART A.

​PART C: Calculate the G for this cell at 298K.

A compound has a pKa of 7.4. To 100mL of a 1.0 M solution of this compound at pH 8.0 is added 30 mL of 1.0M hydrochloric acid. What is the resulting pH?

A proton (?? = +?, ?? = 1.0 u; where u = unified mass unit ≃ 1.66 × 10−27kg), a deuteron (?? = +?, ?? = 2.0 u) and an alpha particle (?? = +2?, ?? = 4.0 u) are accelerated from rest through the same potential difference ?, and then enter the same region of uniform magnetic field ?⃗⃗ , moving perpendicularly to the direction of the magnetic field.

A) What is the ratio of the proton’s kinetic energy ?? to the alpha particle’s kinetic energy ???

B) What is the ratio of the deuteron’s kinetic energy ?? to the alpha particle’s kinetic energy ???

C) If the radius of the proton’s circular orbit ?? = 10 cm, what is the radius of the deuteron’s orbit ???

D) What is the radius of the alpha particle’s orbit ???

A realtor in Arlington, Massachusetts, is analyzing the relationship between the sale price of a home (Price in $), its square footage (Sqft), the number of bedrooms (Beds), and the number of bathrooms (Baths). She collects data on 36 sales in Arlington in the first quarter of 2009 for the analysis. A portion of the data is shown in the accompanying table.

a. Estimate the model Price =  β₀ + β₁Sqft + β₂Beds + β₃Baths + ε. (Round Coefficients to 2 decimal places.)

Intercept. Coefficients for each?

Sqft

Beds

Baths

b. Predict the price of a 2,112 square-foot home with two bedrooms and one bathrooms. (Round coefficient estimates to at least 4 decimal places and final answer to the nearest whole number.)

$___?

The maintenance manager at a trucking company wants to build a regression model to forecast the time until the first engine overhaul based on four explanatory variables: (1) annual miles driven, (2) average load weight, (3) average driving speed, and (4) oil change interval. Based on driver logs and onboard computers, data have been obtained for a sample of 25 trucks.

a. Estimate the regression model to predict the time before the first engine overhaul for a truck driven 60,000 miles per year with an average load of 22 tons, an average driving speed of 57 mph, and 18,000 miles between oil changes. (Note that both annual miles driven and oil change interval are measured in 1,000s.)

b. Use the above prediction to calculate and interpret the 90% confidence interval for the mean time before the first engine overhaul.

c. Calculate and interpret the corresponding 90% prediction interval for the time before the first

Cincinnati Paint Company sells quality brands of paints through hardware stores throughout the United States. The company maintains a large sales force who call on existing customers and look for new business. The national sales manager is investigating the relationship between the number of sales calls made and the miles driven by the sales representative. Also, do the sales representatives who drive the most miles and make the most calls necessarily earn the most in sales commissions? To investigate, the vice president of sales selected a sample of 25 sales representatives and determined:

• The amount earned in commissions last month (y)
• The number of miles driven last month (x₁)
• The number of sales calls made last month (x₂)

The information is reported below.

  Click here for the Excel Data File

Develop a regression equation including an interaction term. (Negative amount should be indicated by a minus sign. Round your answers to 3 decimal places.)

Complete the following table. (Negative amounts should be indicated by a minus sign. Round your answers to 3 decimal places.)

Compute the value of the test statistic corresponding to the interaction term. (Negative amount should be indicated by a minus sign. Round your answer to 2 decimal places.)

At the 0.05 significance level is there a significant interaction between the number of sales calls and the miles driven?

This is (not statistically significant, statistically significant) so we conclude that there (is no interaction, is interaction)

Cincinnati Paint Company sells quality brands of paints through hardware stores throughout the United States. The company maintains a large sales force who call on existing customers and look for new business. The national sales manager is investigating the relationship between the number of sales calls made and the miles driven by the sales representative. Also, do the sales representatives who drive the most miles and make the most calls necessarily earn the most in sales commissions? To investigate, the vice president of sales selected a sample of 25 sales representatives and determined:

• The amount earned in commissions last month (y)
• The number of miles driven last month (x₁)
• The number of sales calls made last month (x₂)

Develop a regression equation including an interaction term. (Negative amount should be indicated by a minus sign. Round your answers to 3 decimal places.)

Complete the following table. (Negative amounts should be indicated by a minus sign. Round your answers to 3 decimal places.)

Compute the value of the test statistic corresponding to the interaction term. (Negative amount should be indicated by a minus sign. Round your answer to 2 decimal places.)

Value of the test statistic

At the 0.05 significance level is there a significant interaction between the number of sales calls and the miles driven?

Consider a vapor power cycle as shown below. Steam enters the first turbine stage at 12 MP a, 480 oC, and expands to 2 MP a. Some steam is extracted at 2 MP a and fed to the closed heater. The remainder expands through the second-stage turbine to 0.3 MP a, where an additional amount is extracted and fed into the open heater operating at 0.3 MP a. The steam expanding through the third-stage turbine enters the condenser at a pressure of 6 kP a and leaves the condenser as saturated liquid at 6 kP a. Liquid water leaves the closed heater at 210 oC, 12 MP a, and condensate exiting as saturated liquid at 2 MP a is trapped into the open heater. Saturated liquid at 0.3 MP a leaves the open heater. Assume all pumps and turbine stages operate isentropically. Determine for the cycle: (a) the heat transfer to the working fluid passing through the steam generator, in MW, (b) the heat transfer from the working fluid passing through the condenser, in MW, (c) the thermal efficiency (%), and (d) sketch a T ?s diagram for the entire cycle with labeled states, isobars, and process directions