# Deviation of a gas from ideal gas behaviour

1. Mar 6, 2015

### RightFresh

Hi all, I have a question from a tutorial sheet that I'm stuck with. The question is

Estimate the pressure at which a gas of argon atoms, at a temperature of 300 K, will begin to show deviations from the ideal gas behaviour due to the finite size of the atoms. Answer: Of order 10^9 Pa.

So I tried taylor expanding the hard sphere gas equation: P'(V-b)=NkT, to get P'=P(1+b/V) to first order, where P is the ideal gas pressure. However, I don't know if this is the right approach or just what to do next really. Could someone point me in the right direction please?

2. Mar 7, 2015

### Bystander

What magnitude of deviations?
Please check this number --- it's somewhat beyond ridiculous.

3. Mar 8, 2015

### RightFresh

It just says deviations & that's the answer given

4. Mar 8, 2015

### RightFresh

It just says deviations & that's the answer given

5. Mar 8, 2015

### Bystander

Without some specification of magnitude of departure, there's no way to answer the question. You could make an assumption of 0.1% (or 0.3 to perhaps 1 % for ordinary measurement accuracies), and at the fixed temperature calculate a pressure at which the excluded volume reached that value, but you're never going to see 109 Pa for such a calculation.

Similar Discussions: Deviation of a gas from ideal gas behaviour
{"extraction_info": {"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0, "math_score": 0.8869982361793518, "perplexity": 1168.2300644840998}, "config": {"markdown_headings": true, "markdown_code": true, "boilerplate_config": {"ratio_threshold": 0.18, "absolute_threshold": 10, "end_threshold": 15, "enable": true}, "remove_buttons": true, "remove_image_figures": true, "remove_link_clusters": true, "table_config": {"min_rows": 2, "min_cols": 3, "format": "plain"}, "remove_chinese": true, "remove_edit_buttons": true, "extract_latex": true}, "warc_path": "s3://commoncrawl/crawl-data/CC-MAIN-2017-34/segments/1502886107744.5/warc/CC-MAIN-20170821080132-20170821100132-00648.warc.gz"}