If 6g of pure carbon is completely burned

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Discussion Overview

The discussion revolves around a chemistry problem involving the combustion of carbon and the calculation of the mass of carbon needed to produce a specific amount of heat (39.3 kJ). The focus is on the enthalpy changes associated with the reaction and the methodology for determining the required mass of carbon based on these values.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant poses a question about calculating the mass of carbon needed to produce 39.3 kJ of heat from its complete combustion.
  • Another participant explains that the enthalpy of carbon dioxide is -393.51 kJ/mol and suggests using this value to determine how many moles of carbon dioxide need to be formed to achieve the desired heat output.
  • A question is raised regarding the source of the enthalpy value for carbon dioxide, specifically asking how it was obtained.
  • A subsequent reply indicates that the enthalpy values can be found in charts commonly included in textbooks or available online.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the calculation process, as the initial question remains unresolved and further clarification is sought regarding the enthalpy values.

Contextual Notes

The discussion includes assumptions about the enthalpy of reactants and products, and the reliance on external charts for enthalpy values, which may not be universally accepted or verified within the context of the discussion.

naren11
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Ques: If 6g of pure carbon is completely burned, what mass of carbon must be burned to furnish 39.3 kj of heat?

For this ques, the equation would be C + O_2 \xrightarrow~ C O_2


well, iam stuck after this
 
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well, we know that any reactant and product in its natural state has an enthalpy of zero.
Carbon, and Oxygen gas both are zero,
carbon dioxide has an enthalpy of -393.51 kJ/mol,
so the differenc of enthalpy of the products to the reactants is -393.51 kJ for every 1 mol of carbhon dioxide formed.so now figure out how many moles need to be formed to make 39.3 kJ, and then work backward to get the mols of carbon needed, then from that you can get the mass of the carbon needed.
 
how did u get the enthalpy of carbon, -393.51 kJ/mol, ?
 
I looked it up in a chart I have.
Many textbooks have charts with values of enthalpy, entropy, and free energy for common elements, usually located in the back appendixes or in the chapters pretaining to these values.
You can also find many more complete charts online.
 

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