Writing States in a chemical equation??? (1 Viewer)

[Michaelmoo]

Ok. Basicaly Im really confused about the whole states thing. Are you supposed to write the state of the chemical under normal conditions, or is it the state of the chemical under the conditions of the reaction. For example:

With the combustion of ethanol, the product water is written in text books as in liquid form. But surely, the combustion reaction is conducted at over 100 degrees celcius.... I have another book that says the water formed is in gas form. Which one is right and why???

Also, with the hydration of ethylene, the reactant water is in gas form; although the experiment is conducted at 330 degrees celcius...


Why is this so?? Please help.

Also, does anyone know or have a source that says what the board of studies defines the states as??

 

[bored of sc]

Ok. Basicaly Im really confused about the whole states thing. Are you supposed to write the state of the chemical under normal conditions, or is it the state of the chemical under the conditions of the reaction. For example:

With the combustion of ethanol, the product water is written in text books as in liquid form. But surely, the combustion reaction is conducted at over 100 degrees celcius.... I have another book that says the water formed is in gas form. Which one is right and why???

Also, with the hydration of ethylene, the reactant water is in gas form; although the experiment is conducted at 330 degrees celcius...


Why is this so?? Please help.

Combustion produces products whereby the temperature of the reaction itself is different to the temperature of the products. This is because the reactants are at the temperature of over 100 degrees celcius however the products formed are not.

The same goes for the hydration of ethylene.

 

[Pwnage101]

water can be put at EITEHR (l) or (g) at HSC LEVEL

 

[Michaelmoo]

water can be put at EITEHR (l) or (g) at HSC LEVEL

Are you sure??? Because Chemistry can be really fussy. Its anoying.. I cant seem to get a straight answer from anyone.

What about other chemicals, are they written as their states under the reaction??? Or under standard conditions??? Does it very if your working with products/reactants??

Please help.

 

[Michaelmoo]

Combustion produces products whereby the temperature of the reaction itself is different to the temperature of the products. This is because the reactants are at the temperature of over 100 degrees celcius however the products formed are not.

The same goes for the hydration of ethylene.

Clearly, this statement doesn't make sense, consider the evaporation of water, the product formed is in gas form...

 

[Darnie]

Clearly, this statement doesn't make sense, consider the evaporation of water, the product formed is in gas form...

evaporation of water is a change in state, not a chemical change.
What they are saying is the total amount of energy released causes the temperature to be 100 degrees celcius (or more) but this is irrelevant really at molecular level.

 

[minijumbuk]

I think it's the reactants' state is written as their state before reaction, and products' state written as state after reaction.

 

[Michaelmoo]

I think it's the reactants' state is written as their state before reaction, and products' state written as state after reaction.

Thanks. But does anyone have a definite answer? This questions been bugging me for ages...

 

[Trebla]

It's obviously the individual states of each species as the reaction is occuring. It would be absurd to write otherwise. Some textbooks are actually wrong. If you look hard that's just one of the examples of where textbooks contradict each other. Should that happen again, you're better off searching for a credible scientific source rather than a textbook.

 

[Z787b]

It's obviously the individual states of each species as the reaction is occuring. It would be absurd to write otherwise. Some textbooks are actually wrong. If you look hard that's just one of the examples of where textbooks contradict each other. Should that happen again, you're better off searching for a credible scientific source rather than a textbook.

Wow you must be a good at maths. (i dont need tutoring). I sat ext 1 and 2 in this years HSC. I will be so glad to get anywhere near your marks!!!:wave: