Chemistry, 26.01.2020 16:31, mariposa91

Urea co(nh2)2 as a solid and water as a gas can be made from the reaction of gaseous carbon dioxide and ammonia. if 12.0g of carbon dioxide reacts with 15.0g of ammonia in a reaction vessel, what is the mole fraction of water vapor in the reaction vessel?

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Urea (CO(NH2)2) synthesis:

CO2 + 2NH3 ===> CO(NH2)2 + H2O

Given:

12.0 grams CO2
15.0 grams of NH3

After the reaction:

moles of CO2 = 12 grams / 44g/mol = 0.27 moles = 0.27/1 = 0.27
moles of NH3 = 15 grams/ 17g/mol = 0.88 moles = 0.88/2 = 0.44

The limiting reactant is CO2. Thus, we will base our calculations on the amount of CO2 available.

moles H2O produced = 0.27 moles CO2 * 1 mol/ 1 mol = 0.27 moles H2O
moles Urea produced = 0.27 moles CO2 * 1 mol/1 mol = 0.27 moles Urea

Total moles in the vessel = excess ammonia + H2O + Urea
= (0.44 - 0.27) + 0.27 + 0.27
= 0.71 moles

The mole fraction of water vapor in the reaction vessel is:

0.27 moles water vapor / 0.71 moles = 0.38

answered: Guest

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.

answered: Guest

pre-sliced bread is a relatively recent development in baking technology. previous to that, it was always sold in a bakery in daily-made contiguous loaves with no wrapping, and was moderately perishable, usually being used with a day or two (which is why every bakery had a discounted “day-old” bread table.) therefore, pre-sliced bread would grow stale quickly. the hard crust provided a protective layer, and once the exposed dry slice left from the previous cut was removed, the interior was still soft.

what keeps bread soft is the moisture retained in the crumb (the light spongy part that’s not crust). the reason the crust develops is the surface of the dough gets exposed to hot dry air during baking which browns the outer layer and seals it, preventing all the moisture from escaping the dough. longer exposure to air will also eventually cause your bread to lose flavor and become stale.

people were used to cutting slices as they needed them and storing bread in a specially-made wooden or metal breadbox or pail with a lid to preserve it longer, but the first automatically sliced commercial loaves were produced on july 6, 1928, in chillicothe, missouri, using a machine invented by otto rohwedder, an iowa-born, missouri-based jeweler.[1] pre-sliced bread would indeed dry out, were it not for another 20th century technology: the plastic bag. bread could now be pre-sliced, and if the enclosing bag remains sealed as much as possible, the bread will remain soft and fresh for longer than if sitting unwrapped on a shelf or enclosed in a bread box that is not air-tight. sealed packaging meant bread could also be sold on store shelves and eliminate frequent trips to a bakery.

sealing bread in a plastic bag had another effect: the moisture in the loaf will re-distribute into the crust and soften it, which is sometimes more pleasing in a sandwich - especially for children whose teeth might not yet be strong enough to tear through a hard crust. a homemade loaf of bread can be sealed in a bag overnight and the crust will become soft like store-bought sandwich bread.

these were novel changes in how bread was produced and sold, which led to the coining of the phrase “the greatest thing since sliced bread.”

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Urea co(nh2)2 as a solid and water as a gas can be made from the reaction of gaseous carbon dioxide...