Define the standard enthalpy of formation
The standard enthalpy of formation of a substance is the enthalpy change when one mole of that substance is formed from the most stable allotropes of its elements in their standard states under standard conditions.
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Related Chemistry A Level answers
All answers ▸A buffer solution was formed by mixing 20.0 cm^3 of sodium hydroxide solution of concentration 0.100 mol dm^–3 with 25.0 cm^3 of ethanoic acid of concentration 0.150 mol dm^–3. CH3COOH + NaOH---CH3COONa + H2O Calculate the pH of this buffer solution.
explain why there is a decrease in first ionisation energy between elements phosphorus and sulfur
When aqueous barium chloride is added to a solution containing sulfate ions a white precipitate is formed. i)Write the ionic equation for the formation of this precipitate.
Explain why the first ionisation energy of sulfur is different from that of phosphorus.