bobiska

The Chernobyl reactor accident in what is now Ukraine was the worst nuclear disaster of all time. Fission products from the reactor core spread over a wide area. The primary radiation exposure to people in western Europe was due to the short-lived (half-life 8.0 days) isotope 131I, which fell across the landscape and was ingested by grazing cows that concentrated the isotope in their milk. Farmers couldn't sell the contaminated milk, so many opted to use the milk to make cheese, aging it until the radioactivity decayed to acceptable levels.

How much time must elapse for the activity of a block of cheese containing 131I to drop to 1.0 of its initial value?

The cadmium isotope has a half-life of 462 days. A sample begins with atoms. How many are left after (a) 49 days, (b) 630 days, and (c) 5600 days

A solution of benzene in the solvent tetrahydrofuran has a mole fraction of C6H6 of 0.293. What mass (g) of the solution must be taken if 2220 g of benzene is needed?

other helpful information:

Molar Mass (g/mol)

C6H6 78.12

C4H8O 72.12

Density (kg/m3):

C6H6 878.6

C4H8O 889.2

Name/Formula:

benzene

C6H6

tetrahydrofuran

C4H8O

any help is appreciated. i'm really lost on how to solve this problem.

The pKa of acetic acid, HC2H3O2, is 4.76. A buffer solution was made using an unspecified amount of acetic acid and 0.30 mol of NaC2H3O2 in enough water to make 2.00 L of solution. Its pH was measured as 4.40. How many moles of HC2H3O2 were used?

A. 0.13 mol

B. 0.69 mol

C. 1.37 mol

D. 0.60 mol

E. 0.18 mol

The ionization constant, Kb, for the weak base trimethylamine, (CH3)3N, is 7.4 × 10-5. What is the pH...?

The ionization constant, Kb, for the weak base trimethylamine, (CH3)3N, is 7.4 × 10-5. What is the pH of a 0.040 molar solution of this base?

A. 9.87

B. 8.37

C. 10.70

D. 12.60

E. 11.23

The ionization constant, Kb, for the weak base trimethylamine, (CH3)3N, is 7.4 × 10-5. What is the pH of a 0.040 molar solution of this base?

A. 9.87

B. 8.37

C. 10.70

D. 12.60

E. 11.23

1. Calculate the molarity (M) of a solution of the strong acid HClO4 if the pH is 1.33.

2. Calculate the pH of a 2.74×10-1 M solution of the strong acid CF3CO2H.

3. Calculate the molarity (M) of a solution of the strong base KOH if the pOH is 1.55.

4. Calculate the pOH of a 1.34×10-3 M solution of the strong base KOH.

PLease explain and you do not have to do all of them but any help is appreciated so please do help! :)

At 298 K the value of Kc for the equilibrium represented by the balanced equation is 1.11 x 101. Calculate the value of Kp for the reverse reaction at the same temperature. Express answer in scientific notation.

Can somebody explain how to do this problem? Thank You

A solution of (CH3)2CO in the solvent C2H5OH has a mole fraction of acetone of 0.159. What mass (g) of the solution must be taken if 399 g of (CH3)2CO is needed?

Help is much appreciated

A 0.391 m solution of the solute hexane dissolved in the solvent benzene is available. Calculate the mass (g) of the solution that must be taken to obtain 247 g of CH3(CH2)4CH3.

and

Calculate the mass (g) of the solute C6H6 and the mass (g) of the solvent tetrahydrofuran that should be added to prepare 1.63 kg of a solution that is 1.42 m.

Can somebody please explain how to solve these problems? Your help is much appreciated. :)

A sample of a gas in a cylindrical chamber with a movable piston occupied a volume of 1.40 L when the pressure was 762 torr and the temperature was 26.9 °C. The volume of the system was readjusted to 0.150 L by moving the piston. What was the pressure exerted on the surface of the piston, in atmospheres, by the gas if the temperature of the system remained constant?

Three spheres having the same volume are filled with gases at the same temperature and pressure. The gas in sphere A is pure hydrogen, the gas in sphere B is pure carbon monoxide, but the gas in sphere C is a mixture of hydrogen and carbon monoxide. Based on the gas laws and molecular formulas, all three spheres contain the same number of molecules.

A mixture of 5.00 mol of neon and 3.00 mol of nitrogen occupy a volume of 36.0 L in a vessel where the total pressure is 6.00 atm. The partial pressure of the neon in the container is...

A sample of a gas was isolated in a gas containment bulb on a manifold used in this type work. The volume of the bulb was 1.524 L. The temperature was 28.40 °C, and the manifold pressure was 637.6 torr. What volume, in liters, would this gas sample occupy at STP?

Please explain

A gas sample occupies a volume of 18.86 L when the temperature is 35.2 °C and the pressure is 735.5 torr. How many moles of gas are in the sample?

Can somebody explain how to find the answer?

An open-end mercury manometer was constructed from a U-shaped tube. In a particular measurement, the level in the end connected to the gas container, on which the experiment was being conducted, measured 76.2 cm above the U-neck, while the level in the open end (to the atmosphere) was 23.8 cm above the U-neck. The outside air pressure in the laboratory was measured as 754 torr. What is the pressure in the gas container?

Can somebody explain how to find the answer please ?

Hi, I really need a way to get to UMBC, but it is so far from my home and don't say something like stay on campus because that is not an option, so if you know how to get from Montgomery county to baltimore county please help!

hurry hurry! need an answer fast!