02/08/18

explain how the dissolving of sodium hydroxide can be exothermic, whereas for ammonium chloride the process is endothermic.
when a solid substance dissolves, two processes are of prime importance: the breaking way of particle from the solid and the joining of solute and solvent particles. in the terms of these two... more
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02/08/18

Are there only about 385 different elements
I think it's only 118. Not sure
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02/08/18

Can a scientific model take a simple concept and strive to make it more complex?
Quick question!
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02/08/18

For the reaction ABC + D ⇌ AB + CD, ΔHorxn = -38.6 kJ/mol and Ea(fwd)=297.5 kJ/mol. Assuming the reaction occurs in one step, calculate Ea(rev).
For the reaction ABC + D ⇌ AB + CD, ΔHorxn = -38.6 kJ/mol and Ea(fwd)=297.5 kJ/mol. Assuming the reaction occurs in one step, calculate Ea(rev).  Please show work
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02/08/18

Molecular Formula
Histamine has the following percent composition: 54% C, 8.1% H, 37.9% N. The molar mass of the entire compound is 111 g/mol. what is the molecular formula of histamine?
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02/08/18

Three queries about expanded octets!
∆ Why can some elements have expanded octets?? Is the only explanation that "the central atom uses its d orbital?"   ∆ If yes, why can't any element use its "d" orbital when its in the center and... more
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02/07/18

How do I solve this AP Chemistry problem on the decomposition of HI(g)?
The activation energy for the decomposition of HI (g) to H2 (g) and I2 (g) is 186 kJ/mol. The rate constant at 555K is 3.52×10^-7 L/mol•s. What is the rate constant at 645K?
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02/07/18

How do I solve this Chemistry problem on activation energy and calculating the value of k?
 The reaction (CH3)3CBr+ OH==>(CH3)3COH+Be   In a certain solvent is first order with respect to (CH3)3CBr and zero order with respect to  OH-. In several experiments, the rate constant k was... more
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02/07/18

How do I solve this Chemistry problem on activation energy?
The rate constant  for the gas phase decomposition of N2O5 has the following temperature dependence    T (K)       k (s^-1)               4.9×10^-3 338.        5.0×10-4 318         ... more
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02/07/18

If the rate of O2 is 0.20 mol/L what is the rate of KClO3
2KClO3-->3O2+2KCl   2. What is the KCl? 
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02/07/18

An experiment was conducted using a 2M KCl solution
An experiment was conducted using a 2M KCl stock solution. There was 1L of stock KCl solution and 480ml of distilled water at the beginning of the experiment, and there is only 125 ml of stock and... more
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02/07/18

What is the area of a football field?
A football field is 100 yards long (1 yard is very close to the length of a meter), by 53 yards wide. 
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02/07/18

What is the longest wavelength seen in the visible absorption spectrum of Li+2 at ordinary temperatures?
The Rydberg constant for Li+2 is 2.18 x 10-18 J. What is the longest and shortest wavelengths seen in the visible absorption spectrum of Li+2 at ordinary temperatures? Also, calculate the... more
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02/07/18

Explain how you know its ionic
Explain it 
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02/06/18

What volume, in millileters, of a 0.151M HI solution is needed to neutralize 68.2mL of a 0.146M Ba(OH)2 solution?
I am trying to figure out this question by the M1V1=M2V2 equation and I know there are 2 mol of HI to 1 mol of Ba(OH)2.  Any help would be appreciated.  Thank you.
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02/06/18

If 8.09 mL of .40M NiSO4 is mixed with 2.13 mL distilled water, calculate the [Ni2+] in the resulting solution
How do you calculate the Nickel in the resulting solution?
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02/06/18

A researcher is using a compound microscope with an eypiece magnification of 10X. He is using the high power magnification (40X) to examine the mitochondria of
A researcher is using a compound microscope with an eypiece magnification of 10X. He is using the high power magnification (40X) to examine the mitochondria of liver cells. How many times are the... more
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02/05/18

A 577 mL NaCl solution is diluted to a volume of 1.12 L and a concentration of 6.00 M . What was the initial concentration?
need help solving equations
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02/05/18

How much water?
If the volume of hydrogen is 56 and the volume of oxygen is 82, how much water can be produced? (Note: the volume ratio of hydrogen to oxygen is 2 to 1.)
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02/05/18

A chemist is using 377 of a of acid and water. If 16.6% of the solution is acid how many milliliters of acid are there? Round your answer to the nearest tenth
Want to know how to find the answer.
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02/05/18

A road salter dispenses 125 kg of salt every 30.2 seconds How many kilograms of salt would be dispensed if the machine was in constant operation for 15 minutes?
 hi could someone help me out with this question please.   A road salter dispenses 125 kg of salt every 30.2 seconds How many kilograms of salt would be dispensed if the machine was in constant... more
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02/05/18

is it true Foods that allow microorganisms to grow are called parasites.
I don't know the answer and I would like some help. I think the anwser is true.
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02/05/18

Please help me solve this chemistry question!
how many grams of PbCl2 are produced when 1.4 moles of NaCl and 3.3 moles of Pb(NO3)2 are used? Molar Mass- PbCl2=278.106 NaCl=58.443 Pb (NO3)2=331.208
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02/05/18

Indicate the number of significant figures in 2.7x10-3
Indicate the number of significant figures in 2.7x10-3
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02/04/18

Why does each atom produce only specific colours?
colour understanding
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