J.R. S.

Biology

11/05/20

animals bodies get some carbon atoms from water

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Chemistry

11/04/20

Carbon-14 has a radioactive half-life of 5730 years. If an organism has 10 g of carbon-14 remaining in its body from a sample that originally had 80 grams in its body, how old is the organism?

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Chemistry

11/04/20

trontium-90 has a life of 29 days. If a sample that originally had 1000 grams of Strontium-90 has decayed to 15 grams. APPROXIMATELY how old is the sample?

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Chemistry

11/04/20

Phosphorus-32 has a half life of 2 weeks. After 8 weeks, what percentage of a sample of phosphorus-32 remains undecayed?

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Chemistry Chem

11/04/20

chemistry class

Consider this reaction.A+B⟶ABWhich three of these factors will not increase the rate of the reaction ? a. decreasing the kinetic energyb. increasing the temperaturec. increasing the concentration... more

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Chemistry Chem

11/04/20

chemistry class

How many milliliters of 11.5 M HCl(aq) are needed to prepare 190.0 mL of 1.00 M HCl(aq)?

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Chemistry

11/04/20

The water level in a graduated cylinder initially at 215 mL rises two 285 mL after a piece of lettuce emerged what is the mass in grams of the lead

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Chemistry

11/04/20

Wavelength/frequency calculations

A. A local AM radio station broadcasts at a frequency of 593 kHz.Calculate the wavelength at which it is broadcasting.Wavelength =BLANK mI know this (1 kHz = 10 3 sec -1)B. A local FM radio station... more

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Chemistry

11/04/20

Standard enthalpy formation

A scientist measures the standard enthalpy change for the following reaction to be 160.2 kJ:CaCO3(s)CaO(s) + CO2(g)Based on this value and the standard enthalpies of formation for the other... more

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Chemistry

11/04/20

Need help with this question :)

A chemical reaction produces 456 mL of nitrogen dioxide (NO2) gas at STP. What is the mass of the gass produced?

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Science Chemistry Biochemistry

11/04/20

How to find the molar enthapy of Ammonium nitrate?

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Chemistry

11/04/20

how many moles of water are theoretically expected to be present in your weighed sample.

Given that the formula predicts that for every 1 mole of K3[Fe(C2O4)3]•3H2O, 3 moles of H2O are present, calculate how many moles of water are theoretically expected to be present in your weighed... more

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Chemistry

11/04/20

How many milliliters of the stock solution do you need to prepare the dilution? How many milliliters of water need to be added?

You are in charge of preparing 25.00 mL of an amoxicillin solution with a concentration of 5.0 g/mL. The lab has a stock solution of ampicillin with a concentration of 80.0 g/mL.

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Chemistry

11/04/20

What is the volume (in mL) of a 0.265 M HCl solution required to completely react with 65.0 grams of Fe?

Fe (s) + 2 HCl (aq) 🡪 FeCl2 (aq) + H2 (g)

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Chemistry

11/04/20

Calculate how many grams of solution are needed to provide 2.50 grams of sulfuric acid.

A chemist needs 2.50 grams of sulfuric acid (H2SO4, MM = 98.08 g/mol) for a reaction, and she only has access to a 15.0% m/v H2SO4 solution (d = 1.84 g/mL). Calculate how many grams of solution... more

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Chemistry

11/04/20

Write the formulas of the products, including states, and balance the equations.

a) ___K2SO4(aq) + ___ BaCl2(aq) 🡪 ______________________________________________________ b) ___ NH4OH(aq) + ___ Ca(NO3)2(aq) 🡪 ______________________________________________________

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Chemistry

11/04/20

The solubility of AlCl3 in the water at 20°C is 45.8 g of solute per 100 g of water. Determine if the following solutions, maintained at 20°C, are either saturated (S) or unsaturated (U).

a) 37.8 g of AlCl3 in 50.0 g of water _________ b) 57.0 g of AlCl3 in 200.0 g of water _________

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Chemistry

11/04/20

convert the mass

Given the exact mass of sample that you weighed out in step 1.1 and 1.2, convert this mass of K3[Fe(C2O4)3]•3H2O into moles of K3[Fe(C2O4)3]•3H2O.mass:.104 g initial- 17.8 mlfinal- 30.7 mlvolume-... more

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Chemistry

11/04/20

What volume of concentrated ammonia would you dilute to 1.50 L to obtain a solution of 0.178 M. The concentrated ammonia solution has a specific gravity of 0.90 and is 27% (w/w).

Give your answer in mL to one decimal place.

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Chemistry

11/04/20

What is K for a reaction if ∆G° =-221.1 kJ/mol at 25°C? (R = 8.314 J/mol ･ K)

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Biology Chemistry Toxicology

11/03/20

How to prepare solutions of various chemical concentrations/dilutions?

Hello, I'm not sure how to prepare solutions of the concentrations: 0.1, 5, 10, 100 micromolar of chemical where the stock chemical should be at 1000X of the final concentration. I need 50... more

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Chemistry

11/03/20

I need help with this question

1.) Oxygen is collected by water displacement at an atmospheric pressure of 750.0 torr and a temperature of 25 degrees celsius. What is the pressure of the oxygen in torr?2.) A chemical reaction ... more

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Chemistry

11/03/20

I need help with this

A gas at STP is cooled to -125 degrees celsius. What is its pressure in torr? (Consider the values of STP to be exact to three significant figures.)

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Chemistry

11/03/20

direct relationship between absorbance and concentration

For monochromatic radiation, the expression of the direct relationship between absorbance and concentration in the form: Abs = ebc (where: e = molar absorptivity, b= cell path length, and c =... more

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Chemistry

11/03/20

Need help with this question. Convert temperatures to Kelvin

1.)At 20 degrees celsius, a gas has a volume of 0.20 meter cube. The gas is heated until its volume doubles. What is its new temperature in Celsius degrees?2.)A volume of 30 L of oxygen is cooled... more

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animals bodies get some carbon atoms from water

Carbon-14 has a radioactive half-life of 5730 years. If an organism has 10 g of carbon-14 remaining in its body from a sample that originally had 80 grams in its body, how old is the organism?

trontium-90 has a life of 29 days. If a sample that originally had 1000 grams of Strontium-90 has decayed to 15 grams. APPROXIMATELY how old is the sample?

Phosphorus-32 has a half life of 2 weeks. After 8 weeks, what percentage of a sample of phosphorus-32 remains undecayed?

chemistry class

chemistry class

The water level in a graduated cylinder initially at 215 mL rises two 285 mL after a piece of lettuce emerged what is the mass in grams of the lead

Wavelength/frequency calculations

Standard enthalpy formation

Need help with this question :)

How to find the molar enthapy of Ammonium nitrate?

how many moles of water are theoretically expected to be present in your weighed sample.

How many milliliters of the stock solution do you need to prepare the dilution? How many milliliters of water need to be added?

What is the volume (in mL) of a 0.265 M HCl solution required to completely react with 65.0 grams of Fe?

Calculate how many grams of solution are needed to provide 2.50 grams of sulfuric acid.

Write the formulas of the products, including states, and balance the equations.

The solubility of AlCl3 in the water at 20°C is 45.8 g of solute per 100 g of water. Determine if the following solutions, maintained at 20°C, are either saturated (S) or unsaturated (U).

convert the mass

What volume of concentrated ammonia would you dilute to 1.50 L to obtain a solution of 0.178 M. The concentrated ammonia solution has a specific gravity of 0.90 and is 27% (w/w).

What is K for a reaction if ∆G° =-221.1 kJ/mol at 25°C? (R = 8.314 J/mol ･ K)

How to prepare solutions of various chemical concentrations/dilutions?

I need help with this question

I need help with this

direct relationship between absorbance and concentration

Need help with this question. Convert temperatures to Kelvin

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