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Chemistry

A Level

Use the following data to explain why NaCl is soluble in water: ∆H = +31 kJmol-1, S(Na+(aq)) = 320.9 JK-1mol-1, S(Cl-(aq)) = 56.5 JK-1mol-1, S(NaCl(s)) = 72.1 JK-1mol-1 Are there any temperatures at which you would not expect NaCl to dissolve?

This is a nice simple calculation question which explores some basic thermodynamic principles and begins to apply them to simple reactions (in this case, solid salt dissolving in water) allowing predictio...

Answered by Kieran R. • Chemistry tutor

7042 Views

How can one differentiate between the organic compounds propanal (CH3CH2CHO) and propanone (CH3COCH3)?

React a sample of each compound with Tollens reagent. The aldehyde (propanal) will be oxidised to a carboxylic acid (propanooic acid) and will form a silver mirror. No change will be observed with the ket...

Answered by Julie T. • Chemistry tutor

3575 Views

What is the difference between exothermic and endothermic?

Exothermic and Endothermic are opposite reactions. All reactions need energy to be put in to start them off, this is called the activation energy, but th...

Answered by • Chemistry tutor

1620 Views

In the reaction (SO₂ + 2H₂S → 3S + 2H₂O), 44.3g of SO₂ are mixed with 44.3g of H₂S. Calculate the maximum mass of sulfur that could be formed.

1. Check if the equation is balanced, luckily this one is! 2. Check if any unit conversions are needed. All masses are in grams, so no problem there. 3. Using (moles = mass ÷ Mr), calculate...

Answered by Kundai V. • Chemistry tutor

3049 Views

Describe the features of a benzene ring that define its reactivity. How does phenol differ from this?

The six carbon atoms in benzene are arranged in a planar ring, with one hydrogen atom bonded to each carbon. Each carbon atom has 4 valence electrons, and uses three of them to form single bonds with the ...

Answered by Elizabeth F. • Chemistry tutor

3498 Views