Document wD8L6mBM5KQjRmEoxnG4ZyQyJ

1319 (2 1) C, C, TT =1 T By the Law of Partial Pressures, (3) C, = op, And by Raoult's Law, (4) p, = F,Pf Combine (3) and (4) to obtain (5) C, = aF,p,. Combining (1), (2,1) and (5), we obtain (6) F.p,. T T FiPi F*ptT, T7+ , FnPn* + --1 n and solving for T, (6 1) T F,p,, + F,p;. + EsEc + EsBca. T, T, + + F,,p,,. , PnPn* T* n i =n E F.P.- Subscripts 1,2, n relate the above quantities to components 1,2, n, respectively Subscnpt i refers to an arbitrary component from 1 to n Absence of subscnpt relates the quantity to the mixture Solution to be applied when there is a reservoir of the solvent mixture whose composition does not change appreciably by evaporation Exact Arithmetic Solution of Specific Mixture Mol wt Density T p at 25 C Mol frac tion in half-andhalf solu tion by volume Trichloro ethylene (1) 131 4 1 46 gm/ml 100 73mm Hg 0 527 Methylchloroform (2) 133 42 l 33 gm/ml 350 125mm Hg 0 473 T = Threshold Limit Value in ppm C = Vapor concentration in ppm p = Vapor pressure of component m solution Vapor pressure of pure component F = Mol fraction of component in solution a = A constant of proportionality F,p,. = (0 527) (73) =38 2 Fjpr -- (0 473) (125) = 59 2 382 + 592 1 ** 512 + 12 100 350 (97 4) (350) 193 0 (974) (350) 133 8 + 59 2 .7,, T = 177 ppm (Note difference in TLV when account is taken of vapor pressure and mol fraction in comparison with above example where such account is not taken 2 A mixture of one part of (1) parathion (TLV, 0 1) and two parts of (2) EPN (TLV, 0 5) c.+ 9l 01 05 C,,, = 3C, C, 2C,_3C, 010 5 Tm 7C, 3C, 0 5 Tm 15 * -- = 021 mg/cu m 1C TLV for Mixtures of Mineral Dusts For mixtures of biologically active mineral dusts the general formula for mixtures ma> be used With the ex ception of asbestos, pure minerals are assigned TLV of 2 5, 20 or 50 For a mixture containing 80 per c'ent talc and 20 per cent quartz, the TLV lor 100 per cent of the mixture "C" is given by TLV=orir84mpptf 20 + 2 5 Essentially the same result will be ob tained if the limit of the more (most) toxic component is used provided the effects are