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4 years ago

The Russian chemist who designed the periodic table that was similar to the Periodic Table used today was _______________-

1 answer:

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Dmitri Mendeleev, he realized that the physical and chemical properties of elements were related to their atomic mass and arranged them into groups (columns)

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Which of these electron transitions correspond to absorption of energy and which to emission?

Elan Coil [88]

Answer:

n = 5 to n = 6 absorption

n = 9 to n = 6 emission

n = 6 to n = 4 emission

n = 6 to n = 7 absorption

Explanation:

According to the Bohr's model of the atom. An electron in an atom may absorb energy and move from a lower energy level to a higher energy level. This requires absorption of energy that is equal to the energy difference between the two levels.

Similarly, an electron may move from a higher to a lower energy level, releasing energy that is equal to the energy difference between the higher and the lower level. This is known as emission.

Hence, if the electron is moving from a lower energy level to a higher energy level, an absorption has taken place, e.g n = 5 to n = 6

When an electron moves from a higher energy level to a lower energy level, an emission has taken place e.g n = 9 to n = 6

5 0

3 years ago

Which statement best explains why heating a liquid affects its viscosity?

Artyom0805 [142]

Answer:

Explanation:

took test I'm pretty sure and found respond else where

5 0

3 years ago

Read 2 more answers

Which of the following transition is considered the phase<br> change from water to steam?

Alexandra [31]

Answer:

the transition from water to steam is call evaporation.

Explanation:

water evaporates or vaporizes and turns into steam this typically happens when heat meets with the water. an example would be if you boil water steam will release from the pot, or when it rains, snows, etc (precipitation) the water evaporates and the ground dries.

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3 years ago

How many moles of Al are necessary to form 23.6 g of AlBr₃ from this reaction: 2 Al(s) + 3 Br₂(l) → 2 AlBr₃(s) ?

Gnoma [55]

Answer:

0.088 mole of Al.

Explanation:

First, we shall determine the number of mole in 23.6 g of AlBr₃.

This is illustrated below:

Mass of AlBr₃ = 23.6 g

Molar Mass of AlBr₃ = 27 + 3(80) = 267 g/mol

Mole of AlBr₃ =.?

Mole = mass/Molar mass

Mole of AlBr₃ = 23.6 / 267

Mole of AlBr₃ = 0.088 mol

Next, we shall writing the balanced equation for the reaction.

This is given below:

2Al(s) + 3Br₂(l) → 2AlBr₃(s)

From the balanced equation above,

2 moles of Al reacted with 3 mole of Br₂ to 2 moles AlBr₃.

Finally, we shall determine the number of mole of Al needed for the reaction as follow:

From the balanced equation above,

2 moles of Al reacted to 2 moles AlBr₃.

Therefore, 0.088 mole of Al will also react to produce 0.088 mole of AlBr₃.

4 0

3 years ago

In order to make 0.500 L of a 0.475 M solution, you will need to weigh out how many grams of sucrose (MM = 342 g/mol)?

elixir [45]

The first step to solve this problem is to multiply the volume of solution times its concentration to find the number of moles needed, remember that M=mol/L:

$0.500L\cdot\frac{0.475mol}{L}=0.2375mol$

Now, use the molar mass of sucrose to find the number of grams needed to make the solution. This is, multiply the number of moles needed times the molar mass:

$0.2375mol\cdot\frac{342g}{mol}=81.225g$

It means that to make 0.500L of a 0.475M you will have to weigh 81.225g of sucrose.

4 0

1 year ago