02/11/19

The half-life for the radioactive decay of calcium-47 is 4.5 d. If a sample has an activity of 1.9 μCi after 27 d, what was the initial activity, in microcuries, of the sample?
The half-life for the radioactive decay of calcium-47 is 4.5 d. If a sample has an activity of 1.9 μCi after 27 d, what was the initial activity, in microcuries, of the sample?
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02/11/19

How many molecules (not moles) of NH3 are produced from 6.36*10^-4g of H2
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02/11/19

Chemistry question

Suppose a sample of helium at 20 degrees Celsius occupies a volume of 9.00 L at a pressure of 6.85 atm. What volume does this helium sample occupy if the pressure is reduced to 6.21 atm while... more
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02/10/19

200 mg/L C12H22O11 mg/L as C;

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02/10/19

What is the pressure of 1.9 mols of nitrogen gas in a 9.45 L tank and at a temperature of 228K
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02/10/19

For the following reaction, if O2 is used up at a rate of 1.45Mhr, what is the rate of formation of H2O?
For the following reaction, if O2 is used up at a rate of 1.45 M/hr, what is the rate of formation of H2O?4NH3+5O2→4NO+6H2O
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02/10/19

Chemistry Le Chat question
SO2(g) + NO2(g)  SO3(g) + NO (g)At a given temperature, analysis of an equilibrium mixture found [SO2] = 4.00 M, [NO2] = 0.500 M, [SO3] = 3.00 M, and [NO] = 2.00 M. (a) What is the new equilibrium... more
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02/10/19

At 1 atm, how much energy is required to heat 79.0 g of H2O(s) at –20.0 °C to H2O(g) at 131.0 °C?
At 1 atm, how much energy is required to heat 79.0 g of H2O(s) at –20.0 °C to H2O(g) at 131.0 °C?
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02/10/19

The root-mean-square velocity of a gas molecule is
The root-mean-square velocity of a gas molecule isa) directly proportional to the square root of its temperature in Kb) inversely proportional to its kinetic energyc) directly proportional to the... more
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02/10/19

An environmental engineer analyzes a sample of air contaminated with sulfur dioxide. To a 500 mL sample of air at 700 torr and 38C, she adds 20.00 mL of 0.01017 M aqueous iodine, which reacts as follo
An environmental engineer analyzes a sample of air contaminated with sulfur dioxide. To a 500 mL sample of air at 700 torr and 38°C, she adds 20.00 mL of 0.01017 M aqueous iodine, which reacts as... more
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02/10/19

Calculate the percentage of CaCO3 present in the sample.
a sample of CaCO3 of mass 2.8g was reacted with 75 cm3 of 1.0 mol/dm3 hydrochloride acid. The resulting solution was completely transferred into 250 cm3 of volumetric flask and the mixture made up... more
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02/10/19

Write the symbol for the element that meets the following conditions:

Blank has 4 electrons in shell 2Blank has five 3p electrons Blank has 1 electron in the 3d subshellsBlank has 2 electrons in the 5p subshellBlank completes the 6s subshell
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02/10/19

Help with Isotopes

Isotope: Sulfer-31What is the isotope symbol? Protons? Neutrons? Electrons? I don't understand how to do isotopes at all.
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02/10/19

Chem stuff good stuff
You make a solution by mixing 40.3 grams of MgCl2 with 750.0 grams of water. What is the molality of the solution?
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02/10/19

Chemistry problem
A student makes a solution that is 4.5 m. If she used 100 kg of water, how many moles of solute did she use?
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02/10/19

For the following reaction, to get the rate of formation of H2O, what must we multiply the rate of consumption of O2 by?
For the following reaction, to get the rate of formation of H2O, what must we multiply the rate of consumption of O2 by?4NH3+5O2→4NO+6H2OReport your answer as a fraction.
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02/09/19

What is the isotope for
12 C 6
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02/09/19

While cooking pasta, some of the salted water spills onto the gas burner.

The gas flame momentarily changes to a bright orange color. Explain what happened.
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02/09/19

How to make a solution of a certain molarity?
Let's say I have an unlimited supply of some pure product, such as Ascorbic Acid (C6H8O6).I will mix it with some deionized water. If I wanted make a specific solution of a certain molarity, would... more
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02/09/19

Circle the type of glassware that is the most precise.

a. 10 mL graduated cylinder b. 100 mL graduated cylinder c. 100 mL beaker Explain why.
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02/09/19

If the smallest marking of a graduated cylinder is in the tenths place, to what place should the measurement be made?

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02/09/19

Units of volume can be milliliters or cubic centimeters.

Which unit would normally apply to liquids? Regularly-shaped solids? Irregularly-shaped solids?
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02/09/19

What is meant by “volume by displacement?”

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02/09/19

word problem chem
In a normal person, the level of glucose is about 85 mg/100 mL of blood. If an average body contains 11 pints of blood, how many grams and how many pounds of glucose are present in the blood?
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02/09/19

One of the following liquids is miscible with the organic solvent carbon tetrachloride, formula CCl4. Identify the liquid.
One of the following liquids is miscible with the organic solvent carbon tetrachloride, formula CCl4. Identify the liquid.bromine, Br2water, H2Oglycerolnitric acid, formula HNO3
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