Answer: Soaps are sodium or potassium fatty acids salts, produced from the hydrolysis of fats in a chemical reaction called saponification. Each soap molecule has a long hydrocarbon chain, sometimes called its 'tail', with a carboxylate 'head'.
Explanation: Saponification is an exothermic chemical reaction—which means that it gives off heat—that occurs when fats or oils (fatty acids) come into contact with lye, a base. In this reaction, the triglyceride units of fats react with sodium hydroxide or potassium hydroxide and are converted to soap and glycerol.
B. It is open to change as new evidence or data is discovered. If scientists discover new evidence, they must modify their theories to conform with the new data.
A. is <em>incorrect</em>. Scientific laws are so well established that there can be no exceptions.
C. is <em>incorrect</em>. A scientific theory is the collective judgement of scientists as to the best explanation for a phenomenon. A new observation may require modification of the theory.
D. is <em>incorrect</em>. Advancements in technology can provide new evidence that requires new explanations.
Answer:
2.60 g of H₂ and 20.8 g of O₂ are produced in the decomposition of 23.44 g of water
Explanation:
Water decomposition is:
2H₂O → 2H₂ + O₂
We convert the mass of water, to moles:
23.44 g . 1 mol/18 g = 1.30 moles
Ratio is 2:2 with hydrogen and 2:1 with oxygen. Let's make rules of three:
2 moles of water can produce 2 moles of hydrogen gas and oxygen gas
Then, 1.30 moles will produce:
(1.30 . 2) /2 = 1.30 moles of H₂
(1.30 . 1) /2 = 0.65 moles of O₂
We convert the moles to mass
1.30 moles of H₂ . 2g / 1mol = 2.60 g of H₂
0.65 moles of O₂ . 32 g / 1 mol = 20.8 g of O₂
Answer:
B is False
Explanation:
In physical chemistry we always look from system's perspective, so if we heat something ΔH is positive and if the system gives heat out then ΔH is negative.
A. We have to give energy to benzene to evaporate it. Statement true.
B. If heat is absorbed then the enthalpy must be positive.
C. The heat is absorbed then ΔH is positive.
D. Usually for burning heat is exposed from system. So enthalpy is negative.
E. Obvious
