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3 years ago

Why should you prefer dry ashing to wet ashing of food sample such as cabbage

Chemistry

1 answer:

julia-pushkina [17]3 years ago

8 0

Answer:

Wet ashing is primarily used in the preparation of samples for subsequent analysis of specific minerals . It breaks down and removes the organic matrix surrounding the minerals so that they are left in an aqueous solution

Explanation:

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The gauge pressure inside a vessel is ‐40kPa, at an elevation of 5000m. a) What is the absolute pressure? b) At this elevation,

hoa [83]

Answer:

a) Pabs = 48960 KPa

b) T = 433.332 °C

Explanation:

Pabs = Pgauge + d*g* h

∴ d = 1000 Kg/m³

∴ g = 9.8 m/s²

∴ h = 5000 m

∴ P gauge = - 40 KPa * ( 1000 Pa / KPa ) = - 40000 Pa; Pa≡Kg/m*s²

⇒ Pabs = - 40000 Kg/ms² + ( 1000 Kg/m³ * 9.8 m/s² * 5000 m )

⇒ Pabs = 48960000 Pa = 48960 KPa

a) at that height and pressure, we find the temperature at which the water boils by means of an almost-exponential graph which has the following equation:

P(T) = 0.61094 exp ( 17.625*T / ( T + 243.04 ))......P (KPa) ∧ T (°C)....from literature

∴ P = 48960 KPa

⇒ ( 48960 KPa / 0.61094 ) = exp ( 17.625T / (T+ 243.04))

⇒ 80138.803 = exp ( 17.625T / ( T + 243.04))

⇒ Ln ( 80138.803) = 17.625T / ( T + 243.04))

⇒ 11.292 * ( T + 243.04 ) = 17.625T

⇒ 11.292T + 2744.289 = 17.625T

⇒ 2744.289 = 17.625T - 11.292T

⇒ 2744.289 = 6.333T

⇒ T = 433.332 °C

3 0

3 years ago

I. Three different representations of glucose are given below. Identify each type of model.

Free_Kalibri [48]

Answer:

Ball and stick model is 3D and has the atoms depicted as different Coloured balls Conected to each other by "sticks"

fischer projection has the atoms on the side coming out of the plane, the atoms at the ends going behind (going away from you)

bond line notation Is the most common it does not show the C or H bonds but instead carbons are represented by the bends

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2 years ago

A bomb calorimetric experiment was run to determine the enthalpy of combustion of ethanol. The reaction is The bomb had a heat c

gulaghasi [49]

Answer:

The enthalpy of combustion of ethanol in kJ/mol is -1419.58 kJ/mol.

Explanation:

The heat absorbed by the bomb and water is equal to the product of the heat capacity and the temperature change. Working with this equation, and assuming no heat is lost to the surroundings, we write :

qcal= Ccal × ΔT= 490 J/K × 276.7 K= 135,583 J = 135.58 kJ

Note we expressed the temperature change in K, because the heat capacity is written in K.

Now that we have the heat of combustion, we need to calculate the molar heat.

Because qsystem = qrxn + qcal and qrxn = -qcal, the heat change of the reaction is -135.58 kJ.

This is the heat released by the combustion of 4.40 g of ethanol ; therefore, we can write the conversion factor as 135.58 kJ/ 4.40 g.

The molar mass of ethanol is 46.07 g, so the heat of combustion of 1 mole of ethanol is :

molar heat of combustion= -135.58 kJ/4.40 g x 46.07 g/ 1 mol= -1419.58 kJ/mol

Therefore, the enthalpy of combustion of ethanol in kJ/mol is -1419.58 kJ/mol.

3 0

4 years ago

Two unknown compounds are tested. Compound 1 contains 15.0g of hydrogen and 120.0g of oxygen. Compound 2 contains 2.0g of hydrog

ivann1987 [24]

Answer:

The both compounds are different.

Explanation:

In order to confirm weather both compounds are same we will check the mole ration. If it is same the compounds will be same.

Given data:

For compound 1.

Mass of hydrogen = 15 g

Mass of oxygen = 120 g

Moles of hydrogen and oxygen = ?

Number of moles of hydrogen = 15 g/ 1g/mol = 15 mol

Number of moles of oxygen = 120 g/ 16 g/mol = 7.5 mol

Total number of moles = 22.5 mol

% of hydrogen = 15 /22.5 × 100 = 66.7%

% of oxygen = 7.5 / 22.5× 100 = 33.3%

For compound 2:

Mass of hydrogen = 2 g

Mass of oxygen = 32 g

Moles of hydrogen and oxygen = ?

Number of moles of hydrogen = 2 g/ 1g/mol = 2 mol

Number of moles of oxygen = 32 g/ 16 g/mol = 2 mol

Total number of moles = 4 mol

% of hydrogen = 2 /4 × 100 = 50%

% of oxygen = 2 / 4× 100 = 50%

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3 years ago

Which statement best describes the movement of atoms in solid

ser-zykov [4K]

Atoms according to the kinetic molecular theory, are described in a solid to simply be vibrating in fixed positions, and not moving rapidly in the container. Because of this, they take a fixed volume and have fixed shape.

7 0

3 years ago

Why should you prefer dry ashing to wet ashing of food sample such as cabbage​

Why should you prefer dry ashing to wet ashing of food sample such as cabbage