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Chemistry
GCSE

When do halogens displace each other in solutions of their salts?

More reactive halogens displace less reactive halogens. The more reactive halogens are those at the top of the group, as their outer electron shells (negatively charged) are closer to the nucleus (positiv...

AP
3688 Views

What is the Avogadro constant and what are moles?

The Avogrados constant the number of atoms in a mole. This is 6.02 x10^23.
The number of moles are calculated through diving the mass (g) by the relative molecular mass of an element.

DT
Answered by Devina T. Chemistry tutor
3734 Views

Explain how the different dyes in ink are separated by chromatography

As the water (the solvent) moves up the paper it carries the ink with it, but the dyes in the ink are differently soluble in the solvent AND the dyes are differently attracted to the paper, therefore the ...

JC
Answered by Jack C. Chemistry tutor
6222 Views

What is the Bohr electron configuration of Oxygen? And further O2- ?

In order to assign O's e- configuration we need to find it on the periodic table. We can see it is on the 2nd period and in group 6 (also sometimes called 16). This means it fills 2 shells and has 6 valen...

HG
Answered by Henry G. Chemistry tutor
9165 Views

Given the mass number of Aluminium is 27 and the mass number of Oxygen is 16, how many moles of Al2O3 are in 30g? (3 significant figures)

Molar Mass of Al2O3 = 27+27+16+16+16 = 102Mass = mol*Mr so mol = Mass/Mrmol = 30/102 = 0.294117... = 0.294 moles

TG
Answered by Toby G. Chemistry tutor
2930 Views

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