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3 years ago

8 points

Chemistry

2 answers:

AveGali [126]3 years ago

8 0

Burning fossil fuels
Mining

Vladimir79 [104]3 years ago

6 0

Answer:

Burning fossil fuels

Mining

Using fertilizers

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Which focuses on the composition of matter

riadik2000 [5.3K]

There is no info for anyone to answer this

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3 years ago

A chemist reacted 17.25 grams of sodium metal with an excess amount of chlorine gas. The chemical reaction that occurred is show

Afina-wow [57]

<u>Answer:</u> The actual yield of the product is 38.57 g

<u>Explanation:</u>

The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:

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

We are given:

Given mass of Na = 17.25 g

Molar mass of Na = 23 g/mol

Putting values in equation 1, we get:

$\text{Moles of Na}=\frac{17.25g}{23g/mol}=0.75mol$

For the given chemical reaction:

$2Na+Cl_2\rightarrow 2NaCl$

By stoichiometry of the reaction:

2 moles of Na produces 2 moles of NaCl

So, 0.75 moles of Na will produce = $\frac{2}{2}\times 0.75=0.75mol$ of NaCl

We know, molar mass of $NaCl$ = 58.44 g/mol

Putting values in above equation, we get:

$\text{Mass of NaCl}=(0.75mol\times 58.44g/mol)=43.83g$

The percent yield of a reaction is calculated by using an equation:

$\% \text{yield}=\frac{\text{Actual value}}{\text{Theoretical value}}\times 100$ ......(1)

Given values:

Percent yield of the product = 88 %

Theoretical value of the product = 43.83 g

Plugging values in equation 1:

$88\% =\frac{\text{Actual yield}}{43.83g}\times 100\\\\\text{Actual yield}=\frac{88\times 43.83}{100}=38.57g$

Hence, the actual yield of the product is 38.57 g

3 0

3 years ago

What is the temperature change if 400 J of energy is added to 10 grams of water

Gemiola [76]

The temperature change if 400 J of energy is added to 10 grams of water is 9.57°C.

<h3>How to calculate temperature change?</h3>

The temperature change of a calorimeter can be calculated using the following expression:

E = mc∆T

Where;

E = energy in joules
m = mass
c = specific heat capacity = 4.18J/g°C
∆T = change in temperature

400 = 10 × 4.18 × ∆T

400 = 41.8∆T

∆T = 400/41.8

∆T = 9.57°C

Therefore, the temperature change if 400 J of energy is added to 10 grams of water is 9.57°C.

Learn more about change in temperature at: brainly.com/question/11464844

3 0

3 years ago

How many electrons does the element Zn have?

Rashid [163]

The answer would be 30

5 0

3 years ago

Which of the following observations indicates that there is a small, dense, positively charged part in the center of an atom?

ser-zykov [4K]

Answer:

Option D

Explanation:

Rutherford deduced that the atomic nucleus was positively charged because the alpha particles that he fired at the metal foils were positively charged, and like charges repel. Alpha particles consist of two protons and two neutrons, so they are positively charged. In Rutherford's experiments most of the alpha particles passed straight through the foil without being deflected. However, occasionally the alpha particles were deflected in their paths, and rarely the alpha particles were deflected backward at a 180 degree angle.

Since like charges repel, Rutherford concluded that the cause of the deflections of the positively charged alpha particles had to be something within the atom that was also positively charged. Rutherford concluded from his metal foil experiments that most of an atom is empty space with a tiny, dense, positively charged nucleus at the center that contains most of the mass of the atom.

7 0

3 years ago