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Chemistry
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Define the term enthalpy of reaction

A chemical reaction occurs when bonds are broken and formed between atoms. Energy is taken in in order to break bonds; when a bond is formed the molecule becomes more stable, so energy is given out. The e...

HK
Answered by Harry K. Chemistry tutor
2498 Views

Why do elements give off coloured light when heated?

When elements are heated, it causes their electrons to become excited. Electrons exist in discrete energy levels, and these energy levels are unique to each element. When the electrons are excited by heat...

GC
Answered by Gemma C. Chemistry tutor
13309 Views

Why are zinc and Scandium not transition metals?

A transition metal is defined as an element that forms a stable ion with incompletely filled d orbitals. Scandium forms a 3+ ion with no electrons in its d orbitals and zinc forms a 3+ ion with completely...

EO
Answered by Ellie O. Chemistry tutor
28186 Views

The mass of a balloon is 0.02g before it is filled with air. After it is blown up with air the mass is 0.04g. Assuming oxygen makes up 21% of air, calculate the number of moles of oxygen in the balloon.

After the balloon has been blown up with air it increased its size by 0.02 g (Final mass - initial mass = mass of the air).We are told that of oxygen takes up 21% of air. Therefore, we need to work out 21...

GS
Answered by Greta S. Chemistry tutor
2617 Views

Describe the bonding in sodium chloride

Sodium chloride is an ionic compound formed by the strong ionic attractions between positively charged sodium ions (which have lost one electron) and negatively charged chloride ions (which have gained an...

MF
Answered by Matthew F. Chemistry tutor
3564 Views

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