# Posts by Massiel

Total # Posts: 14

**chemistry**

The half live of Iodine-131 is 8 days. if you started out with 40 mg sample of iodine-131, then what would be the mass of the sample after 32 days? please show your work

**Differential Equations!**

I'm struggling solving this separable differential equations: (du/dv) = ((uv+u)/(uv+v)) I multiplied both sides by dv to get on the left side just du and cancel out dv, but after that don't know where to go. I've tried integration by parts but it doesn't look ...

**physics**

A sphere is fired downwards into a medium with an initial speed of 40 . Part A If it experiences a deceleration of , where is in seconds, determine the distance traveled before it stops.

**probability**

My daughter had the same problem today... The probability is 1/3... If its a fair game then all of the factors have equal opportunity to occur.

**chemistry**

A sound power level reading of 127 dB was taken near a construction site where chippers were being used. When all but one of the chippers stopped working, the sound power level reading was 120 dB. Estimate the number of chippers in operation when the reading of 127 was ...

**algebra**

thanks!

**algebra**

A sound power level reading of 127 dB was taken near a construction site where chippers were being used. When all but one of the chippers stopped working, the sound power level reading was 120 dB. Estimate the number of chippers in operation when the reading of 127 was ...

**chemistry**

Thanks!

**chemistry**

If in August 1911 Mme. Curie prepared an international standard containing 20.00 mg of RaCl2, what will the radium content of this standard be in August 2010?

**chemistry**

The activation energy for the reaction in which CO2 decomposes to CO and a free radical oxygen atom, O, has activation energy of 460 kJ mol^-2. The frequency factor is 2 x 1011 s^-1. What is the rate constant for this reaction at 298 K?

**chemistry ASAP please!!**

I got it!!! the answer is 4.6x10^-6

**chemistry ASAP please!!**

One reaction that destroys O3 molecules in the stratosphere is NO + O3 NO2 + O2 When this reaction was studied in the laboratory, it was found to be first order with respect to both NO and O3 with a rate constant of 1.9 x 104 mol L-1S-1. If [NO] = 1.2 x 10-5 mol L-1 ...

**Environmental engineering**

If the BOD5 of a waste is 220 mg/L and the ultimate BOD is 320 mg/L, what is the rate constant?

**Environmental engineering**

Ottawa’s anaerobic digester produces 13 m^3/day of sludge with a suspended solids concentration of 7.8%. What volume of sludge must they dispose of each year if their sand drying beds yield a solids concentration of 35%.

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