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3 years ago

What is melted rock and minerals found beneath earths rust called

1 answer:

3 0

Magma- hot fluid or semifluid material below or within the earth's crust from which lava and other igneous rock is formed by cooling. Hope this helps!

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How is the modern periodic table organized??

Serggg [28]

In mordern periodic table there are all element given in modern periodic table

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3 years ago

Read 2 more answers

A reaction of 41.9 g of Na and 30.3 g of Br2 yields 36.4 g of NaBr . What is the percent yield?

Licemer1 [7]

Answer: The percent yield is, 93.4%

Explanation:

First we have to calculate the moles of Na.

$\text{Moles of Na}=\frac{\text{Mass of Na}}{\text{Molar mass of Na}}=\frac{41.9g}{23g/mole}=1.82moles$

Now we have to calculate the moles of $Br_2$

${\text{Moles of}Br_2} = \frac{\text{Mass of }Br_2 }{\text{Molar mass of} Br_2} =\frac{30.3g}{160g/mole}=0.189moles$

${\text{Moles of } NaBr} = \frac{\text{Mass of } NaBr }{\text{Molar mass of } NaBr} =\frac{36.4g}{103g/mole}=0.353moles$

The balanced chemical reaction is,

$2Na(s)+Br_2(g)\rightarrow 2NaBr$

As, 1 mole of bromine react with = 2 moles of Sodium

So, 0.189 moles of bromine react with = $\frac{2}{1}\times 0.189=0.378$ moles of Sodium

Thus bromine is the limiting reagent as it limits the formation of product and Na is the excess reagent.

As, 1 mole of bromine give = 2 moles of Sodium bromide

So, 0.189 moles of bromine give = $\frac{2}{1}\times 0.189=0.378$ moles of Sodium bromide

Now we have to calculate the percent yield of reaction

$\%\text{ yield}=\frac{\text{Actual yield}}{\text{Theoretical yield}}\times 100=\frac{0.353 mol}{0.378}\times 100=93.4\%$

Therefore, the percent yield is, 93.4%

3 0

3 years ago

You find apiece of limestone on ahike. what substances are likely to have formed that rock?

enyata [817]

Limestone is mainly made up of calcium carbonate, CaCO3. When it is heated, it breaks down to form calcium oxide and carbon dioxide. Calcium oxide reacts with water to produce calcium hydroxide. But if u wanna know how it is formed? It's formed by erosion and weathering which is a type of 'Sedimentary Rock'. Erosion and weathering, carried rocks and end up at the sea or ocean. Which is the end way to go! At there, rocks combined by adding more and more just under the sea. The combination of rocks made it harden. First, it was just small little eroded particles end up at the sea. But at last, it became a very hard rock which isn't easy to break!

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3 years ago

A chocolate bar weighs 4.00 ounces. If the chocolate delivers 2.78 calories per gram, how many

dimulka [17.4K]

Answer:

40.79

Explanation:

an ounce is equal to approximately 28.3 grams.

if you have 4 ounces then it would be equal to about 113.4 grams. then you would divide that by 2.78 which will equal about 40.8

6 0

3 years ago

What do chemists use percent yield calculations for in the real world?

STALIN [3.7K]

Answer:

C. To determine how efficient reactions are.

D. To determine how much reactant they need.

Explanation:

When you are doing a reaction, you are hoping for a percent yield to close of 100%. You make the reaction and determine how many product you obtain. If you know the percent yield of a reaction you can calculate the amount of reactant you need to obtain a determined amount of product.

Having this in mind:

A. To balance the reaction equation. false. To calculate percent yield you need to balance the reaction before. You don't use percent yield to balance the reaction

B. To determine how much product they will need. false. You determine how much product you obtain after the reaction. How much product you need is independent of percent yield

C. To determine how efficient reactions are. true. A way to determine efficience of a reaction is with percent yield. An efficient reaction has a high percent yield.

D. To determine how much reactant they need. true. If you know percent yield of a reaction you can know how many reactant you must add to obtain the amount of product you want.

8 0

3 years ago