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Sever21 [200]
3 years ago
7

An element is made up of ______.

Chemistry
2 answers:
mamaluj [8]3 years ago
7 0
An element is made up of atoms!
fredd [130]3 years ago
4 0

Answer:

one type of atom

Explanation:

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A sample of a substance has a mass of 7.5 g and a volume of 2.5 cubic centimeters. What is the object’s density?
Inga [223]

Answer:

option A is the correct answer .

Explanation:

as density = mass per unit volume

density = 7.5/2.5 = 3 gm / cm³ ..is the answer ...

pls mark my answer as brainlist plzzzz and plz vote

7 0
3 years ago
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What might go wrong while heating a substance<br> with a candle?
GaryK [48]

Answer:

the wax melts

Explanation:

because i don't know

7 0
2 years ago
Read 2 more answers
Find percent yield:
saveliy_v [14]

<u>Answer:</u> The percent yield of the reaction is 91.8 %

<u>Explanation:</u>

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

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

  • <u>For B_5H_9 :</u>

Given mass of B_5H_9 = 4.0 g

Molar mass of B_5H_9 = 63.12 g/mol

Putting values in equation 1, we get:

\text{Moles of }B_5H_9=\frac{4g}{63.12g/mol}=0.0634mol

  • <u>For oxygen gas:</u>

Given mass of oxygen gas = 10.0 g

Molar mass of oxygen gas = 32 g/mol

Putting values in equation 1, we get:

\text{Moles of oxygen gas}=\frac{10g}{32g/mol}=0.3125mol

The chemical equation for the reaction of B_5H_9 and oxygen gas follows:

2B_5H_9+12O_2\rightarrow 5B_2O_3+9H_2O

By Stoichiometry of the reaction:

12 moles of oxygen gas reacts with 2 moles of B_2H_5

So, 0.3125 moles of oxygen gas will react with = \frac{2}{12}\times 0.3125=0.052mol of B_2H_5

As, given amount of B_2H_5 is more than the required amount. So, it is considered as an excess reagent.

Thus, oxygen gas is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

12 moles of oxygen gas produces 5 moles of B_2O_3

So, 0.3125 moles of oxygen gas will produce = \frac{5}{12}\times 0.3125=0.130moles of water

Now, calculating the mass of B_2O_3 from equation 1, we get:

Molar mass of B_2O_3 = 69.93 g/mol

Moles of B_2O_3 = 0.130 moles

Putting values in equation 1, we get:

0.130mol=\frac{\text{Mass of }B_2O_3}{69.63g/mol}\\\\\text{Mass of }B_2O_3=(0.130mol\times 69.63g/mol)=9.052g

To calculate the percentage yield of B_2O_3, we use the equation:

\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100

Experimental yield of B_2O_3 = 8.32 g

Theoretical yield of B_2O_3 = 9.052 g

Putting values in above equation, we get:

\%\text{ yield of }B_2O_3=\frac{8.32g}{9.052g}\times 100\\\\\% \text{yield of }B_2O_3=91.8\%

Hence, the percent yield of the reaction is 91.8 %

6 0
4 years ago
How many moles of water as a gas can be formed 2.45 L
Alex17521 [72]

Answer:

0.11mole

Explanation:

Let us assume that the condition is at standard temperature and pressure(STP);

 Given parameters:

        Volume of water  = 2.45L

   Unknown:

       Number of moles found in this volume of water  = ?

Solution;

 At STP;

                 Number of moles  = \frac{volume of gas}{22.4}

 Input the parameters and solve;

                  Number of moles of water  = \frac{2.45}{22.4}   = 0.11mole

The number of moles of water found is  0.11mole

4 0
3 years ago
Water exhibits high levels of cohesion due to the polarity of the molecule (positively and negatively charged sides). given this
nalin [4]
Covalent bonds and it is between the hydrogens (hydrogen bonds)
7 0
4 years ago
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