Discussion List

Verified by AlloprofGrade 4 • 2yr.
Pourquoi la lune atelle des phases différentes

Verified by AlloprofSecondary V • 2yr.
thank you so much. I also have this question that is related to the first question.

Verified by AlloprofSecondary V • 2yr.
This is my chemistry question. Can someone pls help me.

Verified by AlloprofPostsecondary • 2yr.
I'm trying to do my chemistry lab and I don't understand how I'm supposed to calculate the pH of a solution using thee ICE table without having the Ka.

Verified by AlloprofSecondary V • 2yr.
My chemistry homework question is:
The combustion of 0.500 g of propane (C3H8) causes a variation of 10.0°C in a calorimeter whose heat capacity is 2.312 kJ/°C. What is the molar heat of combustion of propane?

Verified by AlloprofSecondary V • 2yr.
I need help with secondary 5 chemistry homework. Can anyone help me?

Verified by AlloprofSecondary III • 2yr.
What is the simplest way to explain entropy? Like, what is it and what do people use it for?

Verified by AlloprofSecondary V • 3yr.
I have to find the number of molecules contained in 0.365 moles of caffeine (C8H10N4O2), I need an explanation please!!!

Verified by AlloprofSecondary V • 3yr.
Hello I have a question to have a better understanding of BoyleMariotte's law!
if the gas pressure doubles, how does the volume vary? and I would like to have the explanation of the answer also please
thank you

Verified by AlloprofSecondary V • 3yr.
Good afternoon
My question is how to calculate the H + ion concentration of the solution ph = 10.70... Could you help me?

Verified by AlloprofSecondary V • 3yr.
Based on the molar mass of a gas, what can I say about its speed of diffusion?
thank you

Verified by AlloprofSecondary V • 3yr.
Am I right when I say: "at a given temperature, the kinetic energy of two different gases is the same"

Verified by AlloprofSecondary V • 3yr.
Hey!
Is there other combustible gas than CH4 and H2?
Thank you,

Verified by AlloprofSecondary V • 3yr.
I need to explain why when we look at a laser ray, we can't see its trajectory, but when chalk powder floats in the air in front of it, we can suddenly see the ray. Can anyone help me? Thank you!

Verified by AlloprofSecondary V • 3yr.
At 25 degrees Celcius, the volume of a gas is 4,6L at a pressure of 98 kPa. What will be its volume if we triple its pressure without changing its temperature?

Verified by AlloprofSecondary V • 3yr.
How can I go from Celcius to Kelvin?

Verified by AlloprofSecondary IV • 3yr.
Hello!
The density of a gas can vary, but why?
thank you!

Verified by AlloprofSecondary IV • 3yr.
Hello, I don’t understand why salt melts ice. Could you explain it to me using the atomic model please?

Verified by AlloprofSecondary V • 3yr.
True or false  Only endothermic reactions absorb energy.

Verified by AlloprofSecondary V • 3yr.
Hi,
Why are we increasing the amount of carbon dioxide in greenhouses?

Verified by AlloprofSecondary V • 3yr.
Hello,
I have the following equation at equilibrium :
HF = H+ + F Kc = 6,7 x 10^4
How do I know if the direct or the indirect reaction is favored?

Verified by AlloprofSecondary IV • 3yr.
What is the meaning of a negative temperature when using the calorimetry formula (Q=mc△t)?

Verified by AlloprofSecondary V • 3yr.
Good morning,
What is the difference between an elastic and an unelastic collision?
Thank you

Verified by AlloprofSecondary V • 3yr.
Hi Alloprof,
Do gas particles still have kinetic energy below 0 degrees Celcius?

Verified by AlloprofSecondary V • 3yr.
Hello,
What is the normal atmospheric pressure?

Verified by AlloprofSecondary IV • 3yr.
I don't understand how to solve this problem:
The atomic mass of isotope # 1 of element Ab is 73 au. The atomic mass of isotope # 2 of the element Ab is 76 au. The atomic mass of isotope # 3 of the element Ab is 74 au. The relative frequencies of each isotope are 10%, 80% and 10%, respectively.
Find the average atomic mass.
Thank you!

Verified by AlloprofSecondary IV • 3yr.
What is the periodicity of properties?

Verified by AlloprofSecondary IV • 3yr.
Emilie suffers from diabetes. Therefore, after having lunch, traces of glucose (C6H12O6) can be found in her blood. What is the total mass of sugar that can be found in her blood before it reaches a concentration of 10 mmol / L? (hint: volume of blood = 5L)

Verified by AlloprofSecondary IV • 3yr.
How do you distinguish between metals, nonmetals and metalloids in the periodic table?

Verified by AlloprofSecondary IV • 3yr.
Hi!
I have an exercise that asks me to determine the mass of sodium hydroxide (NaOH) in a basic solution by titrating it with a 1.8 mol / L acidic solution. The titration shows a neutralization volume of 30 mL for the acid and an initial volume of 20 mL for the base. I am not sure how to find the mass.