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3 years ago

Is francium found in nature or lab?

Chemistry

1 answer:

ddd [48]3 years ago

8 0

Answer:

It was the last element first discovered in nature, rather than by synthesis. Outside the laboratory, francium is extremely rare, with trace amounts found in uranium and thorium ores, where the isotope francium-223 continually forms and decays

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Given that the freezing point depression constant for water is 1.86°c kg/mol, calculate the change in freezing point for a 0.907

melamori03 [73]

Answer : The correct answer for change in freezing point = 1.69 ° C

Freezing point depression :

It is defined as depression in freezing point of solvent when volatile or non volatile solute is added .

SO when any solute is added freezing point of solution is less than freezing point of pure solvent . This depression in freezing point is directly proportional to molal concentration of solute .

It can be expressed as :

ΔTf = Freezing point of pure solvent - freezing point of solution = i* kf * m

Where : ΔTf = change in freezing point (°C)

i = Von't Hoff factor

kf =molal freezing point depression constant of solvent. $\frac{^0 C}{m}$

m = molality of solute (m or $\frac{mol}{Kg}$ )

Given : kf = 1.86 $\frac{^0 C*Kg}{mol}$

m = 0.907 $\frac{mol}{Kg}$ )

Von't Hoff factor for non volatile solute is always = 1 .Since the sugar is non volatile solute , so i = 1

Plugging value in expression :

ΔTf = 1* 1.86 $\frac{^0 C*Kg}{mol}$ * 0.907 $\frac{mol}{Kg}$ )

ΔTf = 1.69 ° C

Hence change in freezing point = 1.69 °C

5 0

3 years ago

How many carbon atoms are in the smallest cyclic hydrocarbon?

SOVA2 [1]

There are 3 carbon atoms

3 0

3 years ago

Read 2 more answers

PLEASE HELP AND EXPLAIN!Calculate the energy required to heat 187.0 g of ammonia from 36.1 °C to 52.9 °C. Assume the specific he

Alenkinab [10]

Answer:

$E=1.48x10^4J$

Explanation:

Hello!

In this case, since the energy implied in a heating process is computed by using the following equation:

$E=mC(T_f-T_i)$

Whereas m is the mass, C the specific heat and T the temperature. In such a way, by plugging in the given mass, specific heat and temperatures, we obtain the following energy:

$E=187.0g*4.703\frac{J}{g\°C} (52.9\°C-36.1\°C)\\\\E=1.48x10^4J$

Considering that the specific heat can by used by unit of °C or K because their difference is equivalent.

Regards!

3 0

3 years ago

(CO2) (O2) (He) (N2) (CH4) (Imagine these are balloons with the specified gas inside)

valentina_108 [34]

Answer:

Highest speed: He

Lowest speed: CO2

Explanation:

The rms speed (average speed) of the molecules/atoms in an ideal gas is given by:

$v=\sqrt{\frac{3RT}{M}}$

where

R is the gas constant

T is the absolute temperature of the gas

M is the molar mass of the gas, which is the mass of the gas per unit mole

From the equation, we see that at equal temperatures, the speed of the molecules in the gas is inversely proportional to the molar mass: the higher the molar mass, the lower the speed, and vice-versa.

In this problem, we have 5 gases:

(CO2) (O2) (He) (N2) (CH4)

Their molar mass is:

CO2: 44 g/mol

O2: 16 g/mol

He: 4 g/mol

N2: 14 g/mol

CH4: 16 g/mol

The gas with lowest molar mass is Helium (He): therefore, this is the gas with greatest average speed.

The gas with highest molar mass is CO2: therefore, this is the gas with lowest average speed.

8 0

3 years ago

What is science of love?

shtirl [24]

science of love

,EXPLANATION:

The initial happy feelings of being in love is stimulated by 3 chemicals in the brain: noradrenaline that stimulates adrenaline production causing that racing heart and sweaty palms; dopamine, the feel-good chemical; and phenylethylamine that is released when we're near our crush, giving us butterflies in our tummies.

hope this will help u..and plz mark this as brainliest

6 0

2 years ago