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A solution is made by dissolving 10.20 grams of glucose (C6H12O6) in 355 grams of water. What is the freezing point depression o

Ludmilka [50]

Answer:

0.297 °C

Step-by-step explanation:

The formula for the freezing point depression ΔT_f is

ΔT_f = iK_f·b

i is the van’t Hoff factor: the number of moles of particles you get from a solute.

For glucose,

glucose(s) ⟶ glucose(aq)

1 mole glucose ⟶ 1 mol particles i = 1

Data:

Mass of glucose = 10.20 g

Mass of water = 355 g

ΔT_f = 1.86 °C·kg·mol⁻¹

Calculations:

(a) Moles of glucose

n = 10.20 g × (1 mol/180.16 g)

= 0.056 62 mol

(b) Kilograms of water

m = 355 g × (1 kg/1000 g)

= 0.355 kg

(c) Molal concentration

b = moles of solute/kilograms of solvent

= 0.056 62 mol/0.355 kg

= 0.1595 mol·kg⁻¹

(d) Freezing point depression

ΔT_f = 1 × 1.86 × 0.1595

= 0.297 °C

3 0

3 years ago

Purification of copper can be achieved by electrorefining copper from an impure copper anode onto a pure copper cathode in an el

givi [52]

Answer: The amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours

Explanation:

We are given:

Moles of electron = 1 mole

According to mole concept:

1 mole of an atom contains $6.022\times 10^{23}$ number of particles.

We know that:

Charge on 1 electron = $1.6\times 10^{-19}C$

Charge on 1 mole of electrons = $1.6\times 10^{-19}\times 6.022\times 10^{23}=96500C$

$Cu^{2+}+2e^-\rightarrow Cu$

$2\times 96500=193000C$ is passed to deposit = 1 mole of copper

63.5 g of copper is deposited by = 193000 C

$14\times 1000g=14000g$ of copper is deposited by = $\frac{193000}{63.5}\times 14000=42551181 C$

To calculate the time required, we use the equation:

$I=\frac{q}{t}$

where,

I = current passed = 40.0 A

q = total charge = 42551181 C

t = time required = ?

Putting values in above equation, we get:

$40.0=\frac{42551181 C}{t}\\\\t=1063779sec$

Converting this into hours, we use the conversion factor:

1 hr = 3600 seconds

So, $1063779s\times \frac{1hr}{3600s}=295hr$

Hence, the amount of time needed to plate 14.0 kg of copper onto the cathode is 295 hours

3 0

3 years ago

A cathode ray tube is made of glass with a small amount of some kind of gas in it. It has metal electrodes at each end to pick u

Butoxors [25]

Answer:

One of the main uses of the cathode ray tube is in the Cathode ray oscilloscope

Explanation:

Cathode rays are produced when a gas in an evacuated glass at very low pressure and high pressure breaks up into positive and negative ions. the negative ions move towards the anode(positive electrode) while the positive ions move towards the cathode(negative electrode), and there they knock off electrons (which are known as cathode rays) from the metal plate of the cathode.

Cathode ray tubes are mainly used in oscilloscopes, television picture tubes and in computer screens.

The cathode ray oscilloscope is used in a.c. and d.c. voltage measurements, observation of waveforms, time measurements, etc.

5 0

3 years ago

Answer pls pls plss this is my mock

Serggg [28]

Answer:

if this is a mock then just guess

Explanation:

4 0

2 years ago

Which of these solutions will be the best conductor of electricity?

Ymorist [56]

it is answer solution c

5 0

2 years ago

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