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The enthalpy of combusbon for methane at 298.15 K is -726.1 kJ mol-1 .What is its enthalpy of
formation? (given: ∆Hf (C02 ) =-393.5 kJmol-1
and ∆Hf (H2O) = -285.8 kJmol-1·.
The reaction between solid white phosphorus and oxygen produces solid tetraphosphorusdecoxide (P4O10)
A. Write the balanced chemical equation of the reaction
b. Determine the mass of tetraphosphorusdecoxide (P4O10) formed if 26.0 g of phosphorus (P4) and 49.5 g oxygen (O2) are combined.
C. How much of the excess reactant remains after the reaction stops.
The reaction between solid white phosphorus and oxygen producing solid tetraphosphorusdecoxide (P4O10)
Calculate the number of liters occupied at STP of 2.5 mol of nitrogen gas.
A 150 g of ammonium chloride solution is 15.00 % by mass with a density of 1.037 g/mL. Calculate molarity and molality of a solution
A solid compound of molar mass 100 g mol−1 was introduced into a container and heated
to 400 °C. When a hole of diameter 0.50 mm was opened in the container for 400 s, a mass loss of 285 mg was measured. Calculate the vapour pressure of the compound at 400 °C.
In an organic molecular solid, the "free state" mobility of photoinjected holes at room temperature is 0.4 cm²/Vs. Due to a small concen tration of traps at a concentration of 1 part in 108, each having a trap depth of 0.4 eV, the observed mobility is much smaller than this. What is the observed mobility at 250 K? 300 K? 350? What is the characteristic temperature below which one might consider the mobility to be "trap limited"?
Subject: Earth & Life Sciences (Grade 11 (SHS))
Question: How minerals can be used as indicators of specific environmental parameters? Justify your answer. (3 sentences only.)
Quinine (a non-volatile, non electrolyte) has the empirical formula C10H12NO.A sample of
quinine (0.162 g) was mixed with camphor (10.0 g) and the freezing point of the mixture was found to be 175.2 oC. The freezing point of pure camphor was determined to be 177.2 oC.
[Kf (camphor) = 40.0 oC Kg mol-1]
(a) Calculate the freezing point depression of the solution.
(b) Calculate the molality of the quinine.
(c) Calculate the moles of quinine.
(d) Calculate the molar mass of quinine
(e) What is the molecular formula of quinine?
An unknown fraction of organic matter in soil has a molecular mass of 2200 g/mol. It contains 20 carboxyl groups (pka = 5) and 10 phenolic groups (pka = 6). The pH of this soil is 5. What is its CEC? Write a sentence describing how functional groups relate to charge generation in soil.
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#339914 on Dec 2023