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Greeley [361]
3 years ago
11

Your teacher asks you to follow the instructions in a lab to produce several known chemical reactions. During these procedures,

you are required to record any observations that suggest chemical reactions have occurred. Which of these list of observations best describes evidence of chemical reactions?
Chemistry
1 answer:
vova2212 [387]3 years ago
3 0

Answer:

There are five evidences that tell whether a chemical change has occurred. These are change of color, change of odor, change in temperature or energy, formation of gas and formation of a precipitate.

Explanation:

Chemical Change- This is a type of chemical reaction which occurs when the properties of one or more atoms change and results into a<u> newly formed substance. </u>

Let's have a further discussion of the evidences.

1. Change of Color- Color change is caused by the combination of two or more substance with different molecular structures. A popular example of this is the Statue of the Liberty, which is made of copper plates. Due to the exposure of copper to elements like water, it changed color.

2. Change of Odor- This can be best presented with rotting food. During the rotting process, the food undergoes a chemical reaction. The result is a rotten smell.

3. Change in Temperature or Energy- An example of this is the burning of wood. Its change is considered non-reversible.

4. Formation of Gas- This can be best presented with the cake batter (the one being used to make cakes or pancakes). The batter rises which means it is forming gas. This is caused by the reaction of the baking soda and the acid.

5. Formation of a Precipitate- This occurs when two soluble salts combine and their outcome is an insoluble salt (this is the precipitate).

Take note that if any of these evidences occur, then there's definitely a chemical reaction.

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A 0.200 g sample of unknown metal x is dropped into hydrochloride acid and realeases 80.3 mL of hydrogen gas at STP using ideal
s344n2d4d5 [400]

Answer:

The number of mole of the unknown metal is 3.58×10¯³ mole

Explanation:

We'll begin by calculating the number of mole hydrogen gas, H2 that will occupy 80.3 mL at stp.

This is illustrated below:

Recall:

1 mole of any occupy 22.4L or 22400 mL at stp.

1 mole of H2 occupies 22400 mL at stp.

Therefore, Xmol of H2 will occupy 80.3 mL at stp i.e

Xmol of H2 = 80.3/22400

Xmol of H2 = 3.58×10¯³ mole

Therefore, 3.58×10¯³ mole of Hydrogen gas was released.

Now, we can determine the mole of the unknown metal as follow:

The balanced equation for the reaction is given below:

X + 2HCl —> XCl2 + H2

From the balanced equation above,

1 mole of the unknown metal reacted to produce 1 mole of H2.

Therefore, 3.58×10¯³ mole of the unknown metal will also react to produce 3.58×10¯³ mole of H2.

Therefore, the number of mole of the unknown compound is 3.58×10¯³ mole.

5 0
3 years ago
Group 18 noble gases are relatively inert because *
choli [55]

Answer:I believe its A. There noble gasses so there happy with there electron count!

Explanation:

3 0
3 years ago
If a 0.10 M solution of a colored substance has a maximum absorbance at 500 nm and an absorbance of 0.26 M at this wavelength, w
Mashcka [7]
Absorbance is related to the concentration of a substance using the Beer-Lambert's Law. According to this law, absorbance is linearly related to concentration. However, this is only true up to a certain concentration depending on the substance. For this case, we assume that the said law is applicable.

A = kC
Using the first conditions, ewe solve for k.
0.26 = k (0.10)
k = 2.6

A = kC
A = 2.6 (0.20) = 0.52

Therefore, the absorbance at a concentration of 0.20 M and wavelength of 500nm is 0.52.
7 0
3 years ago
A farmer has a large field with one type of
Hoochie [10]

Answer:

Disagree

Explanation:

Biodiversity is having a variety, or a diversity of life. Having one crop is not a variety, therefore this field does not have high biodiversity.

6 0
3 years ago
What is the position of the element ammonia in periodic table?
Rashid [163]
Ammonia isn't an element, it's a compound made by mixing the elements Nitrogen and Hydrogen in the Haber process. Therefore, it isn't on the periodic table
8 0
3 years ago
Read 2 more answers
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