?

A 25.0 mL sample of 0.100 M propanoic acid (HC3H5O2, Ka = 1.3 ✕ 10-5) is titrated with 0.100 M KOH solution. Calculate the pH after the addition of the following amounts of KOH.

24.0 mL

24.5 mL

24.9 mL

25.0 mL

25.1 mL

26.0 mL

28.0 mL

30.0 mL

A father gently places his son on a rotating merry-go-round. The merry-go-round is essentially a disk with a mass of 250 kg and a radius of 2.5 m initially rotating at one revolution every 5.00 seconds. Assume the boy has a mass of 12.0 kg and is placed (without slipping) near the edge of the merry-go-round. Determine the final angular velocity of the merry-go-round/boy system.

Two masses are suspended from a pulley as shown in the figure below (the Atwood machine). The pulley itself has a mass of 0.30 kg, a radius of 0.15 m, and a constant torque of 0.35 m·N due to the friction between the rotating pulley and its axle. What is the magnitude of the acceleration of the suspended masses if m1 = 0.30 kg and m2 = 0.70 kg? (Neglect the mass of the string.)

Two masses are suspended from a pulley as shown in the figure below (the Atwood machine). The pulley itself has a mass of 0.30 kg, a radius of 0.15 m, and a constant torque of 0.35 m·N due to the friction between the rotating pulley and its axle. What is the magnitude of the acceleration of the suspended masses if m1 = 0.30 kg and m2 = 0.70 kg? (Neglect the mass of the string.)

The reaction below in a certain solvent is first order with respect to (CH3)3CBr and zero with respect to OH -.

(CH3)3CBr + OH - (CH3)3COH + Br -

In several experiments, the rate constant k was determined at different temperatures. A plot of ln(k) versus 1/T was constructed resulting in a straight line with a slope of -1.10 ✕ 104 K and y-intercept of 33.5. Assume k has units of s-1.

A)Determine the activation energy for this reaction.

B)Determine the value of the frequency factor A.

C) Calculate the value of k at 25°C.

A 70 kg painter is painting the wall of a building. He stands on a horizontal board of length 5.0 m and mass 15 kg, suspended from vertical ropes attached to each end. If the painter stands 1.5 m from one end of the board, what would the tensions in the ropes be?

tension in rope nearer to the painter(a)

tension in rope further from the painter(b)

A uniform meterstick pivoted at its center has a 85 g mass suspended 21 cm from the pivot point.

(A) How far from the pivot should a 75 g be suspended to put the system in equilibrium?

(B) What mass would have to be suspended 40 cm from the pivot for the system to be in equilibrium?

At 500 K in the presence of a copper surface, ethanol decomposes according to the following equation.

C2H5OH(g) CH3CHO(g) + H2(g)

The pressure of C2H5OH was measured as a function of time and the following data were obtained.

Time (s) PC2H5OH (torr)

0 250.

100. 237

200. 224

300. 211

400. 198

500. 185

Since the pressure of a gas is directly proportional to the concentration of gas, we can express the rate law for a gaseous reaction in terms of partial pressures. Using the above data, deduce the rate law, the integrated rate law, and the value of the rate constant, all in terms of pressure units in atm and time in seconds. Predict the pressure of C2H5OH after 900. s from the start of the reaction. [Hint: To determine the order of the reaction with respect to C2H5OH, compare how the pressure of C2H5OH decreases with each time listing.]

A 1600 kg truck rolls with a speed of 1.6 m/s under a loading bin, and a mass of 3530 kg is deposited in the truck. What is the truck's speed immediately after loading?

Hydrochloric acid (50.0 mL of 0.456 M) is added to 247.0 mL of 0.0800 M Ba(OH)2 solution. What excess ions are left in the solution? OH or H?

What is the concentration of the excess H+ or OH - ions left in this solution?