Tables 2-108 Formic Acid HCOOH

Use the table of Ka values in Appendix E to list the conjugate bases of the following acids in order of increasing base strength formic acid, HCOOH hydrofluoric acid, HF(aq) benzoic acid, CeHsCOOH phenol, CeHsOH. 

Although the D s for U(VI) and tetravalent actinides are very high, the data in Table VII show that formic acid (HCOOH) will readily back-extract these elements as well as Am(III) from all the extractants except in the case of U(VI) with 0(()D[IB]CMPO. 

Most of the gas phase Ci chemistry is elsewhere presented (Chapters 5.3.2.2 and 5.3.3 concerns organic and 2.8.3.2 concerns CO2 and earbonate dissolution). Two species from the heading above, methanol CH3OH and formic acid HCOOH we met as emissions from biomass burning (Table 2.44). Beeause C—O and O—H bonds are much stronger than the C—H bond, OH attaek goes preferable onto C—H (al higher carbon chains preferably at the aC—H) A 5.325 = 7.7 10" cm molecule" s and ks.326... 

This is an expression of Ostwald s dilution law, and the equation can be used to determine K, a, or A°. For example, from Table 15.4, we can calculate A° for formic acid, HCOOH, to be equal to... 

Calculate the pH of a buffer made by dissolving 1 mol formic acid (HCOOH) and 1 mol sodium formate (HCOONa) in 1 L of solution (see Table 9.9). 

Ants release formic acid (HCOOH) when they bite. Use the data in Table 7.2 and the standard enthalpy of combustion for formic acid (AjH = —255 kj/mol) to calculate the standard enthalpy of formation for formic acid. 

From Table 10.1, the pKa for formic acid is 3.75. Assuming little change in the concentrations of acid and base due to the deprotonation of HCOOH, we write... 

Carboxylic acids The smallest carboxylic acid, formic acid, can be measured using infrared spectroscopy (Table 11.2), since it has characteristic absorption bands. As discussed earlier and seen in Fig. 11.33b, mass spectrometry with chemical ionization using SiF5 also revealed HCOOH in an indoor environment (Huey et al., 1998). However, since the sensitivity in these initial studies was about two orders of magnitude less than that for HN03, the detection limit may be about the same as that for FTIR and TDLS. Formic and acetic acids have been monitored continuously from aircraft (Chapman et al., 1995) and their surface flux determined by eddy correlation (Shaw et al., 1998) using atmospheric pressure ionization mass spectrometry. Detection limits are about 30 ppt. 

The formic ° and acetic acid decompositions are probably not unimolecular, intramolecular eliminations as reported. An. 4-factor lower than 10 sec (Table 38, HCOOH-> H2 + CO2) is quite impossible. In addition, decomposition of formic acid dimer, (HCOOH)2 - 2H2O + CO, is equally suspect. The authors... 

A carboxyl group is usually represented in condensed form by writing -COOH. For example, ethanoic acid can be written as CH3COOH. The simplest carboxylic acid consists of a carboxyl group bonded to a single hydrogen atom, HCOOH, shown in Table 22.9. Its formal name is methanoic acid, but it is more commonly known as formic acid. Some insects produce formic acid as a defense mechanism, as shown in Figure 22.10. 

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