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3 years ago

A sample of hydrogen gas occupies 17.5 L at

Chemistry

1 answer:

yuradex [85]3 years ago

5 0

Answer:

0.781 mol

Explanation:

1 mol any gas under STP has volume 22.4 L.

17.5 L * 1 mol/22.4L = 0.781 mol

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Weathering involves the

alisha [4.7K]

Explanation:

Maybe

Physical and chemical breakdown of rocks

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3 years ago

a student used 10 mL water instead of 30 mL for extraction of salt from mixture. How may this change the percentage of NaCl extr

Anit [1.1K]

It will be extracted only 1/3 of NaCl less in 10 mL of water than in 30 mL of water.

If it is known that solubility of NaCl is 360 g/L, let's find out how many NaCl is in 30 mL of water:

360 g : 1 L = x g : 30 mL

Since 1 L = 1,000 mL, then:
360 g : 1,000 mL = x g : 30 mL

Now, crossing the products:
x · 1,000 mL = 360 g · 30 mL
x · 1,000 mL = 10,800 g mL
x = 10,800 g ÷ 1,000
x = 10.8 g

So, from 30 mL mixture, 10.8 g of NaCl could be extracted.

Let's calculate the same for 10 mL water instead of 30 mL.

360 g : 1 L = x g : 10 mL

Since 1 L = 1,000 mL, then:
360 g : 1,000 mL = x g : 10 mL

Now, crossing the products:
x · 1,000 mL = 360 g · 10 mL
x · 1,000 mL = 3,600 g mL
x = 3,600 g ÷ 1,000
x = 3.6 g

So, from 10 mL mixture, 3.6 g of NaCl could be extracted.

Now, let's compare:
If from 30 mL mixture, 10.8 g of NaCl could be extracted and from 10 mL mixture, 3.6 g of NaCl could be extracted, the ratio is:
3.6/10.8 = 1/3

Therefore, it will be extracted only 1/3 of NaCl less in 10 mL of water than in 30 mL of water.

5 0

3 years ago

Two students made the Lewis dot diagrams of NH3. The diagrams are as shown.

Neko [114]

Answer : The correct option is, Only Student B

Explanation :

Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.

In the Lewis-dot structure the valance electrons are shown by 'dot'.

The given molecule is, $NH_3$

As we know that nitrogen has '5' valence electrons and hydrogen has '1' valence electron.

Therefore, the total number of valence electrons in $NH_3$ = 5 + 3(1) = 8

According to Lewis-dot structure, there are 6 number of bonding electrons and 2 number of non-bonding electrons.

The Lewis dot structure of student A is wrong because there is a coordinate bond present between the nitrogen and hydrogen is not covalent.

The correct Lewis-dot structure of $NH_3$ is shown by the student B.

6 0

4 years ago

how do i caculate the trmperature change that 725 grams of aluminum will undergo when 2.35x10^4 Joules of thermal energy are add

sesenic [268]

Answer:

36°C

Explanation:

Given parameters:

Mass of aluminum = 725g

Quantity of heat = 2.35 x 10⁴J

Unknown:

Temperature change = ?

Solution:

To solve this problem, we simply use the expression below:

The quantity of energy is given as:

Q = m C Δt

Q is the quantity of energy

m is the mass

C is the specific heat capacity of aluminum = 0.9J/g°C

Δt is the change in temperature

The unknown is Δt;

Δt = $\frac{Q}{mc}$ = $\frac{2.35 x 10^{4} }{725 x 0.9}$ = 36°C

4 0

3 years ago

A metal in group 1 of the periodic table can become a chemically stable ion by

Mkey [24]

Bonding ionically with a group 7 non-metal

4 0

4 years ago