Chemistry, 02.07.2019 19:20 fatherbamboo

The reaction between potassium chlorate (kcio,) and red phosphorus (p.) takes place when one strikes a match. the products of the reaction are tetraphosphorus decoxide and potassium chloride. if 56.0 grams of kcio, are reacted with an excess amount of red phosphorus, how many grams of p0o and kci can be produced? how much red phosphorus is consumed in the reaction? (15 pts) write the balanced reaction first!

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Amount of tetraphosphorus decoxide formed is 38.60g, amount of potassium chloride formed is 33.99g and amount of red phosphorus consumed in the reaction is 81.48 g.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ....(1)

For potassium chlorate:

Given mass of potassium chlorate = 56.0 g

Molar mass of potassium chlorate = 122.55 g/mol

Putting values in above equation, we get:

$\text{Moles of potassium chlorate}=\frac{56.0g}{122.55g/mol}=0.456mol$

For the given chemical reaction:

$10KClO_3+12P\rightarrow 3P_4O_{10}+10KCl$

Red phosphorus is given in excess . So, it is considered as an excess reagent and potassium chlorate is considered as a limiting reagent.

For tetraphosphorus decoxide:

By Stoichiometry of the reaction:

10 moles of potassium chlorate reacts with 3 moles of tetraphosphorus decoxide

So, 0.456 moles of potassium chlorate will react with = $\frac{3}{10}\times 0.456=0.136moles$ of tetraphosphorus decoxide

Calculating the mass of tetraphosphorus decoxide by using equation 1, we get:

Molar mass of tetraphosphorus decoxide = 283.886 g/mol

Moles of tetraphosphorus decoxide = 0.136 moles

Putting values in equation 1, we get:

$0.136mol=\frac{\text{Mass of tetraphosphorus decoxide}}{283.886g/mol}\\\\\text{Mass of tetraphosphorus decoxide}=38.60g$

For potassium chloride:

By Stoichiometry of the reaction:

10 moles of potassium chlorate reacts with 10 moles of potassium chloride

So, 0.456 moles of potassium chlorate will react with = $\frac{10}{10}\times 0.456=0.456moles$ of potassium chloride

Calculating the mass of potassium chloride by using equation 1, we get:

Molar mass of potassium chloride = 74.55 g/mol

Moles of potassium chloride = 0.456 moles

Putting values in equation 1, we get:

$0.456mol=\frac{\text{Mass of potassium chloride}}{74.55g/mol}\\\\\text{Mass of potassium chloride}=33.99g$

For Red phosphorus (excess reagent)

By Stoichiometry of the reaction:

10 moles of potassium chlorate reacts with 12 moles of red phosphorus.

So, 0.456 moles of potassium chlorate will react with = $\frac{12}{10}\times 0.456=2.631moles$ of red phosphorus

Calculating the mass of red phosphorus by using equation 1, we get:

Molar mass of red phosphorus = 30.97 g/mol

Moles of red phosphorus = 2.631 moles

Putting values in equation 1, we get:

$2.631mol=\frac{\text{Mass of red phosphorus}}{30.97g/mol}\\\\\text{Mass of red phosphorus}=81.48g$

Hence, amount of tetraphosphorus decoxide formed is 38.60g, amount of potassium chloride formed is 33.99g and amount of red phosphorus consumed in the reaction is 81.48 g.

Answer from: Quest

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.”

Answer from: Quest

The answer to your question really depends on three things: how much water you have, how cold it is to start out, and how cold the things around it are. water actually freezes when it gets to 32 degrees fahrenheit (0 degrees celsius), but the time it takes to get there may be different. let's start with the first. if you take two glasses, and fill one with a tiny bit of water, and the other about halfway, then put them both in the freezer, the one with less water will freeze first (you can try this at home, but i recommend using plastic cups and not glass ones). now let's move on to the second part. let's say you have two glasses, and you fill one with really cold water that has been in the refrigerator, and the other with really hot water from the sink. if you put both of them in the freezer, the one that started out colder will freeze first. for the third part, let's imagine that you have two glasses with the same amount of water in them, and the water is at the same temperature. imagine putting one outside on a really really cold day in georgia, and having a friend in alaska put one outside on the same day. since it would be so much colder in alaska, the glass of water there would freeze before yours. so, if you took a tiny bit of really cold water in a glass, and put it outside on a cold day in alaska, it would freeze a lot faster than a big glass of hot water outside on a cold day in georgia.