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2 years ago

What atom has 19 protons and 20 neutrons

2 answers:

4 0

Potassium has 19 protrons and 20 neutrons. We can easily tell this because on The Periodic Table, potassium (symbol "K") is number 19. Meaning it has 19 protons and 19 electrons.

Over [174]2 years ago

3 0

Potassium Does! Hope that helps

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onsider the following reaction: CaCN2 + 3 H2O → CaCO3 + 2 NH3 105.0 g CaCN2 and 78.0 g H2O are reacted. Assuming 100% efficiency

mestny [16]

Answer : The excess reactant is, $H_2O$

The leftover amount of excess reagent is, 7.2 grams.

Solution : Given,

Mass of $CaCN_2$ = 105.0 g

Mass of $H_2O$ = 78.0 g

Molar mass of $CaCN_2$ = 80.11 g/mole

Molar mass of $H_2O$ = 18 g/mole

Molar mass of $CaCO_3$ = 100.09 g/mole

First we have to calculate the moles of $CaCN_2$ and $H_2O$ .

$\text{ Moles of }CaCN_2=\frac{\text{ Mass of }CaCN_2}{\text{ Molar mass of }CaCN_2}=\frac{105.0g}{80.11g/mole}=1.31moles$

$\text{ Moles of }H_2O=\frac{\text{ Mass of }H_2O}{\text{ Molar mass of }H_2O}=\frac{78.0g}{18g/mole}=4.33moles$

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

$CaCN_2+3H_2O\rightarrow CaCO_3+2NH_3$

From the balanced reaction we conclude that

As, 1 mole of $CaCN_2$ react with 3 mole of $H_2O$

So, 1.31 moles of $CaCN_2$ react with $1.31\times 3=3.93$ moles of $H_2O$

From this we conclude that, $H_2O$ is an excess reagent because the given moles are greater than the required moles and $CaCN_2$ is a limiting reagent and it limits the formation of product.

Left moles of excess reactant = 4.33 - 3.93 = 0.4 moles

Now we have to calculate the mass of excess reactant.

$\text{ Mass of excess reactant}=\text{ Moles of excess reactant}\times \text{ Molar mass of excess reactant}(H_2O)$

$\text{ Mass of excess reactant}=(0.4moles)\times (18g/mole)=7.2g$

Thus, the leftover amount of excess reagent is, 7.2 grams.

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3 years ago

What is a polar liquid?

BabaBlast [244]

Polar liquids have both negative and positive ends.

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3 years ago

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A balanced chemical equation must have the same number of which of these on both sides of the equation?

andrew11 [14]

A balanced equation must have the same number of atoms on the both sides of equation.

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2 years ago

Getting a vaccine is safer than taking medication or undergoing surgery. True or false I

Ahat [919]

Answer:

false...

Explanation:

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Suppose a lab group reports a percent yield of sand of 105%. Is it really possible to collect more sand than was originally pres

just olya [345]

The maximum percent of yield should be 100%, so It wasn't possible to make a higher than 100% yield like 105% in this problem. If that happens, it will contradict the law of conservation of energy as you can't create mass.

The increased mass might be produced by impurities. One of the examples would be if you rinse the container and left some water. The water is not calculated as a substrate but will increase the results weight.
There also possibilities that some gas in the air react and produce a solid/liquid material. If you don't weight the gas it would seem that the mass increased.

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3 years ago