299 Answered Questions for the topic chem

Chem Chemistry

11/23/20

For each of the following, indicate if the number of half-lives elapsed is:

For each of the following, indicate if the number of half-lives elapsed is:1. one half-life2. two half-lives3. three half-lives a sample of Ce-141 with a half-life of 32.5 days after 32.5 days a... more

please help on this questions

1.At what temperature was thermal equilibrium reached? How long did it take to arrive at this temperature?2.How does the temperature change within the first 60 seconds of the experiment? Within the... more

11/20/20

thermochemistry problem (please help if u can!)

When 0.467 g of sodium metal is added to an excess of hydrochloric acid, 4950 J of heat are produced. What is the enthalpy of the reaction as written?2Na (s) + 2 HCL (aq) → 2NaCL (aq) + H2 (g)
Chem Chemistry

11/19/20

i need help on this question

The figure is a 3-dimensional representation of an atomic orbital. Which orbital does it represent? three d-orbital a single p-orbital three p-orbitals an s-orbital

i need help on this

SEP Construct an Explanation Describe the chemistry of the fire triangle. How does the fire triangle relate to how fiercely a wildfire burns?  SEP Construct an Explanation How do firefighters use... more

i need help on this chemistry

Describe (in words) how conduction, convection and radiation all take place to heat the room.
Chem Chemistry

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
Chem Chemistry

11/04/20

chemistry class

A solution contains 0.700 g Ca2+ in enough water to make a 1825 mL solution. What is the milliequivalents of Ca2+ per liter (mEq/L) for this solution?
Chem Chemistry

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)?
Chem Chemistry

10/19/20

Calculate the grams of calcium carbonate (CaCO3) that will dissolve in 1.0L of 0.020 M Na2CO3?

Calculate the grams of calcium carbonate (CaCO3) that will dissolve in 1.0L of 0.020 M Na2CO3?Having trouble with this question. Any help would be appreciated!
Chem Chemistry

10/19/20

The solubility product of calcium fluoride ( CaF2 ) is 3.5×10−11. If 2.0 mL of a 0.10 M solution of NaF is added to 128 mL of a 2.0×10−5M solution of Ca(NO3)2 , will CaF2 precipitate?

The solubility product of calcium fluoride ( CaF2 ) is 3.5×10−11. If 2.0 mL of a 0.10 M solution of NaF is added to 128 mL of a 2.0×10−5M solution of Ca(NO3)2 , will CaF2 precipitate?Unsure how to... more

09/21/20

need help with a homework problem, very advanced

Guanine is an essential component of DNA. It contains the elements carbon, hydrogen,nitrogen and oxygen. When 615 mg of guanine is burned, 895 mg of carbon dioxide and 183 mgof water are formed. In... more
Chem Chemistry

09/21/20

Determine the ΔH for the formation of ONE MOLE of each of product in the following equations, include the appropriate sign. C(s) + 4 H2(g) + O2(g) ––––––––––––> 2 CH3OH(g) + 402 kJ ΔH =

I need some help please, I don't understand how to do this question:Determine the ΔH for the formation of ONE MOLE of each of product in the following equations, include the appropriate sign.C(s) +... more
Chem Chemistry

09/21/20

I need some help with a CHEM 12 problem

I really don't understand how to do this question, any help would be greatly appreciated!!Nitrogen monoxide and oxygen gas react to produce nitrogen dioxide according to the following balanced... more

09/18/20

What volume is required to prepare a 2.70 M HCl solution with 50.0 grams of HCl? What is the concentration of each ion?

Please show work as well for a better understanding. :)

Density and Percentage

Battery Acid consists of 31 % (m/m) H2SO4 and has a density of 1.27 g/mL. How many mL of pure H2SO4 must be used to create 5.0 L of battery acid? The density of pure H2SO4 is 1.84 g/mL.

09/11/20

If you burn 33.7g of hydrogen and produce 301g of water, how much oxygen reacted?

In the combustion of hydrogen gas, hydrogen reacts with oxygen from the air to form water vapor.Hydrogen + Oxygen —> WaterIf you burn 33.7g of hydrogen and produce 301g of water, how much... more

what mass of ammonia can be synthesized from 150g of h2?

Can you please show steps as well? thank you!

Iron (II) sulfide contains 36.47% sulfur by mass. If 87.91 g of iron sulfide is made by reacting iron with sulfur, what mass of iron was reacted?

I really need help with this question. Can you please show steps as well? thank you!
Chem Chemistry

08/31/20

what is the the volume in mL

acetone is a common solvent that has a density of 0.7899 g/mL. what volume of acetone, in mililiters, has a mass of 34.2 g?

What is the condensed formula of 3-ethylheptane ?

Please write the condensed formula of 3-ethylheptane in one line.
Chem Science

06/12/20

What steps are needed to make 250.0 mL of a .20 mol/L solution from solid NaOH? And the molar mass of NaOH is 40g/Mol.

i need "a complete response that includes the required mass of the sample and a set of detailed instructions"

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