Which of the substances evaporated first? and Which of the substances evaporated least?

The Geocentric and the Heliocentric models are descriptions of the universe known at the time when these models were developed.

RSB [31]

Answer:The Geocentric and the Heliocentric models are descriptions of the universe known at the time when these models were developed. The main difference between the two models is the perceived center of the known universe. According to the geocentric model, Earth is the center of the known universe

Explanation:I answerd the question before in Earth Science

8 0

2 years ago

A student was asked to prepare 500.0 mL of 6.0 M NaOH. The student measured 120.0 g of NaOH and placed it in a 1000 mL beaker. T

Morgarella [4.7K]

Answer:

The concentration of the solution will be much lower than 6M

Explanation:

To prepare a solution of a solid, the appropriate mass is taken and accurately weighed in a weighing balance and then made up to mark with distilled water.

From

n= CV

n = number of moles m/M( m= mass of solid, M= molar mass of compound)

C= concentration of substance

V= volume of solution

m=120g

M= 40gmol-1

V=500ml

120/40= C×500/1000

C= 120/40× 1000/500

C=6M

This solution will not be exactly 6M if the student follows the procedure outlined in the question. The actual concentration will be much less than 6M.

This is because, solutions are prepared in a standard volumetric flask. Using a 1000ml beaker, the student must have added more water than the required 500ml thereby making the actual concentration of the solution less than the expected 6M.

7 0

3 years ago

NEEEEEEEEEEEEEEEEED HELP

lakkis [162]

<h3> <u>Answer</u></h3>

4. loses 2 electrons

<h3><u>EXPLANATION</u></h3>

Mg²+ has 10 electrons while Mg has 12 electrons.

7 0

2 years ago

If 24.6 grams of lithium react with excess water, how many liters of hydrogen gas can be produced at 301 Kelvin and 1.01 atmosph

andreev551 [17]

Answer: 43.3 l

Explanation:

1) Chemical equation:
2 Li(s) + 2 H₂O (l) → 2LiOH(aq) + H₂ (g)

2) Mole ratios:

2 mol Li : 2 mol H₂O : 2 mol LiOH : 1 mol H₂

3) Number of moles of Li that react

n = mass in grams / atomic mass = 24.6g / 6.941 g/mol = 3.54 moles

4) Yield

Proportion:

2 mol Li / 1 mol H₂ = 3.54 mol Li/ x

⇒ x = 3.54 mol Li × 1 mol H / 2 mol Li = 1.77 mol H₂

4) Ideal gas equation

PV = nRT ⇒ V = nRT / P

V = 1.77 mol × 0.0821 [atm×l / (mol×K)] × 301 K / 1.01 atm = 43.3 l

V = 43.3 l ← answer

7 0

3 years ago

A single-effect evaporator is concentrating a feed of 9072 kg/h of a 10 wt % solution of NaOH in water at temperature of 288.8 K

Aloiza [94]

Answer:

a) steam used = 8440 kg/hr

b) Because as per calculation done in a), Steam is sufficient to evaporate 7257.6 kg/hr water from feed. Since feed is less than this amount, therefore whole water will be evaporated and 100% solid product will be obtained in bottom collection

Explanation:

Saturated steam pressure = 42KPag=1.42 bar

From steam table, Steam temperature = 110 C

Latent heat of this steam = 2230 KJ/kg

Process side pressure = 20 Kpaa = .2 bar

Water latent heat at this Pressue = 2360 KJ/kg

Water boiling Point at this Pressure =60 C

Feed Inlet temperature = 15.6 C

Total Heat required = Heat required to rise feed temperature from 15.6 to 60 degree C + Evaporation of water to concentrate the feed

Total Water evaporation required = 9072*(100-10)/100-9072*.1/.5*.5=7257.6 Kg/hr

Specific heat of feed assumed = 4.2 KJ/kg/K

=> Total heat required = 9072*4.2*(60-15.6)+7257.6*2360=18819682 KJ/hr

LMTD = ((110-60)-(110-15.6))/LN((110-60)/(110-15.6))=69.8 C

U, Overall Heat transfer coefficient = 1988 W/m2/K

Total heat required = U*A*LMTD

=> Area required of evaporator, A=18819682 *1000/3600/1988/59.8=44 m2

Steam used = 18819682/2230=8440 kg/hr

Energy required to condense vaporised feed = 7257.6*2360=17127936 KJ/hr

=> Steam efficiency = (18819682-17127936)/18819682=9%

b) Because as per calculation done in a), Steam is sufficient to evaporate 7257.6 kg/hr water from feed. Since feed is less than this amount, therefore whole water will be evaporated and 100% solid product will be obtained in bottom collection

6 0

3 years ago

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