SATP

At standard ambient temperature and pressure (SATP), which means exactly 25°C (298.15 K) and exactly 1 bar, the conditions commonly used to report data in chemistry, the molar volume of an ideal gas is 24.79 L-mol l, which is about the volume of a cube l ft on a side (Fig. 4.15). The expression standard temperature and pressure (STP) means 0°C and 1 atm (both exactly), the conditions formerly used to report data and still widely used in some calculations. At STP, the molar volume of an ideal gas is 22.41 I.-mol1. Note the slightly smaller value the temperature is lower and the pressure is slightly higher, and so the same amount of gas molecules occupies a smaller volume than at SATP. 

The density, d, of a gas, like that of any substance, is the mass of the sample divided by its volume, d = tn/V. Because the densities of gases are so low, they are usually expressed in grams per liter (g-L ). The density of air, for instance, is about 1.6 g-L-1 at SATP. Because the mass of the sample is equal to the amount in moles times the molar mass, m = nM, and n = PV/RT, it follows that... 

Figure 1.65 SATP reacts with amine-containing proteins or other molecules via its NHS ester end to create protected sulfhydryl derivatives in a manner similar to that of SATA. Deprotection can be done with hydroxy-lamine to free the thiol.

Dissolve the SATP reagent (Molecular Probes) in DMF at a concentration of 65 mM (16mg/ml). Note DMF should be handled in a fume hood. 

Add 10 pi of the SATP solution to each ml of protein or peptide solution. 

Deprotect the acetylated —SH groups as needed by adding 100 pi of 0.5 M hydroxy-lamine hydrochloride in 50mM sodium phosphate, 25 mM EDTA, pH 7.5, to each ml of the SATP-modified protein solution. 

The enthalpy change of a chemical reaction is known as the enthalpy of reaction, AHrxn- The enthalpy of reaction is dependent on conditions such as temperature and pressure. Therefore, chemists often talk about the standard enthalpy of reaction, AH°rxn - the enthalpy change of a chemical reaction that occurs at SATP (25 C and 100 kPa). Often, Alf n is written simply as AW°, The symbol is called nought. It refers to a property of a substance at a standard state or under standard conditions. You may see the enthalpy of reaction referred to as the heat of reaction in other chemistry books. 

Rocket fuel Rocket fuel Rocket fuel Rocket fuel Saran SATP SEl SEl... 

SATP SEl SEl Silver azide Silver fulminate Di-sUver aminotetrazole perchlorate Self-igniting incendiary Self-igniting incendiary... 

The amount of permeated substance can be expressed in mass, mole or volume units. For gases, volume is preferred, expressed as the amount permeating under conditions of standard temperature and pressure (STP), which corresponds to the standard temperature of 273.15 K and standard pressure of 1.01325 105 Pa. The corresponding dimensions for D and S are obtained at the same time from Eq. (9-4). The standard ambient temperature and pressure (SATP) are set at p°= 1 bar= 105 Pa = 0.9678 atm and T = 298.15 K. The data in handbooks however is still mostly expressed with p = 1 atm as standard pressure. For practical purposes the difference between these two conventions is insignificant compared to the variability of the materials themselves. 

The average pressure of the atmosphere at sea level is taken as standard pressure (760 mm Hg = 760 torr = 1 atm = 101.3 kPa). The freezing point of water (0°C or 273 K) is defined as standard temperature. Together, these conditions are referred to as standard temperature and pressure (STP). (See Figure 11.23.) The normal conditions under which we live are referred to as standard ambient temperature and pressure. These conditions are known as SATP, defined as 25°C and 100 kPa. 

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