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the ideal gas

the ideal gas. pV = nRT. p ressure. V olume. n umber of moles. T emperature. pV = nRT. For pV=nRT to work, temperature must be absolute . For an absolute temperature, T=0 means zero energy. Kelvin, K is an absolute temperature. K = o C +273.15. K = o C +273.15.

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the ideal gas

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  1. the ideal gas

  2. pV = nRT pressure Volume number of moles Temperature

  3. pV = nRT For pV=nRT to work, temperature must be absolute. For an absolute temperature, T=0 means zero energy. Kelvin, K is an absolute temperature. K = oC +273.15

  4. K =oC +273.15 What is 100 oC in K to the nearest whole number? What is 100 oC in K to one significant figure? What is 73 K in oC to the nearest whole number? What is 73 K in oC to one significant figure?

  5. pV = nRT pressure is caused by gas moleculeshitting the wall of the container. Volume is size of container. n is the number of moles of gas molecules. R= 8.3 J mol-1 oC-1 Temperature measures the kineticenergy of the gas molecules.

  6. p a n Keeping V and T constant: if we double n, we double p. if we triple n, we triple p. if we halve n, we halve p.

  7. p a T Keeping V and n constant: if we double T, we double p. if we triple T, we triple p. if we halve T, we halve p.

  8. Keeping T and n constant: if we halve V, we double p. if we triple V, we reduce p by a third. if we double V, we halve p. we say p and V are inversely proportional p a V-1 n = constant

  9. deducing the ideal gas law based n the previous proportionality relations p a V-1 p a V-1 n T pV a nT p a n p a T pV = nRT

  10. pV = nRT If we keep T and V constant, if one doubles n what happens to p? If we keep n and T constant, if one doubles V what happens to p? If we keep n and p constant, if one doubles Twhat happens to V? If we keep p and V constant, if one doubles n what happens to T? p doubles, n doubles but V stays constant, what happens to T? p triples, V halves and n doubles, what happens to T?

  11. proportionality relations

  12. directly proportional pV = nRT c = 2p r p an c a r V,T constant

  13. indirectly (inversely) proportional pV = nRT h A= hw w h w h a w-1 Area constant p a V-1 n,T constant

  14. KE is proportional to velocity squared other proportionality relations exist. KE a v2 if velocity doubles, what happens to KE? if velocity triples, whathappens to KE? if velocity halves, what happens to KE? KE = ½ m v2

  15. velocity is proportional to square root of KE. KE = ½ m v2 va KE 2 KE 2 KE _______ _______ v2 = m m if KE quadruples, what happens to v? if KE doubles, what happens to v? if KE halves, what happens to v? v =

  16. Where applicable, please state the proportionality relation between the following pairs of quantities. If no proportionality relation exists, please state so. State also, where possible, the proportionality constants.

  17. V= h x w x d d a w V a w2 x h V a m m is constant V is constant h a 1/w2 Mr. Fantastic

  18. the exponent is 9. 7.2 (± 0.3) x 109 0.3 is the error bar. the digit 7 is the first significant figure. The most important part of a number is the exponent. The second most important part of a number is its first significant figure. The third most important part of a number is the error bar.

  19. proportion- ality relation is a cubed relation 4 p proportionailty constant is 4p/3 ≈ 4. Volume = _____ r3 sphere 3 The most important part of a chemistry equation is the proportionality relation. The second most important part of a chemistry equation is its proportionality constant.

  20. What are the most important parts of the equations below? Please use the proportionality sign in your answers. pV = nRT KE = ½ mv2

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