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3 years ago

1. please answer i really need your help

Chemistry

2 answers:

myrzilka [38]3 years ago

7 0

1. solve the bracket (OH)3= 3 Oxygen, 3 Hydrogen

2. multiply 2Fe with (OH)3= 2*3= 6, 2*3=6

3. solve 2FE3= 2*3= 6FE

4. Add all= 6Fe+ 6oxygen+ 6H= Total atom 18

elixir [45]3 years ago

6 0

Answer:

Explanation:

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How much energy is released when 18.0 g of water at 0°C changes from liquid to solid?

yaroslaw [1]

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7 0

3 years ago

In a thin layer chromatography experiment, a plate of length 9.3 cm was used and a horizontal line was made at 1.45 cm above the

dezoksy [38]

Answer: The $R_f$ value is 0.664

Explanation:

Distance travelled by solvent front = (7.7-1.45)cm = 6.25 cm

Distance travelled by unknown = (5.6-1.45) cm = 4.15 cm

The retention factor or the $R_f$ value is defined as the ratio of distance traveled by the unknown to the distance traveled by the solvent front.

$R_f=\frac{\text {distance travelled by unknown}}{\text {distance travelled by solvent}}$

$R_f=\frac{4.15}{6.25}=0.664$

Thus the $R_f$ value is 0.664

6 0

3 years ago

This is very difficult

Oliga [24]

Answer: C

Explanation:

6 0

3 years ago

1) If the pressure on 2.6 liters of a gas at 860 Torr is increased to 1000 Torr,

LenKa [72]

2.24 liters is the volume of the gas if pressure is increased to 1000 Torr.

Explanation:

Data given:

Initial volume of the gas V1 = 2.6 liters

Initial pressure of the gas P1 = 860 Torr 1.13 atm

final pressure on the gas P2 = 1000 Torr 1.315 atm

final volume of the gas after pressure change V2 =?

From the data given above, the law used is :

Boyles Law equation:

P1V1 = P2V2

V2 = P1V1/P2

= 1.13 X 2.6/ 1.31

= 2.24 Liters

If the pressure is increased to 1000 Torr or 1.315 atm the volume changes to 2.24 liters. Initially the volume was 2.6 litres and the pressure was 860 torr.

6 0

3 years ago

Brass is a substitutional alloy consisting of a solution of copper and zinc. A particular sample of red brass consisting of 79.0

Bas_tet [7]

Answer: The molality and molarity of zinc in the solution is 4.07 m and 28.11 M respectively.

Explanation:

Solute is the substance which is present in smaller proportion in a mixture and solvent is the substance which is present in larger proportion in a mixture.

We are given:

(m/m) % of Cu = 79 %

This means that 79 g of copper is present in 100 grams of alloy.

(m/m) % of Zn = 21 %

This means that 21 g of zinc is present in 100 grams of alloy.

As, zinc is present in smaller proportion. So, it is solute and copper is the solvent.

Calculating molality of zinc:

To calculate molality of the zinc, we use the equation:

$Molality=\frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ in grams}}$

where,

$m_{solute}$ = Given mass of solute (Zinc ) = 21 g

$M_{solute}$ = Molar mass of solute (Zinc) = 65.3 g/mol

$W_{solvent}$ = Mass of solvent (copper) = 79 g

Putting values in above equation, we get:

$\text{Molality of Zinc}=\frac{21\times 1000}{65.3\times 79}\\\\\text{Molality of zinc}=4.07m$

Calculating molarity of zinc:

To calculate volume of a substance, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Density of solution = $8740kg/m^3=\frac{8740kg\frac{1000g}{1kg}}{1m^3\times \frac{10^6cm^3}{1m^3}}=\frac{8740g}{1000cm^3}=8.740g/cm^3$

(Conversion factors used are: 1 kg = 1000 g & $1m^3=10^6cm^3$ )

Mass of solution = 100 g

Putting values in above equation, we get:

$8.740g/cm^3=\frac{100.0g}{\text{Volume of zinc}}\\\\\text{Volume of zinc}=11.44cm^3$

To calculate the molarity of solution, we use the equation:

$\text{Molarity of the solution}=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}$

We are given:

Molar mass of zinc = 65.3 g/mol

Volume of solution = $11.44cm^3=11.44mL$ (Conversion factor: $1cm^3=1mL$ )

Mass of zinc = 21.0 g

Putting values in above equation, we get:

$\text{Molarity of zinc}=\frac{21\times 1000}{65.3\times 11.44}=28.11M$

Hence, the molality and molarity of zinc in the solution is 4.07 m and 28.11 M respectively.

4 0

4 years ago