Which has a greater ionization energy: lithium or bromine? Which has a greater ionization energy: vanadium or sodium?

A 100.00 ml of volume of 0.500 M HCl was mixed with 100.00 ml of 0.500 M KOH in a constant pressure calorimeter. The initial tem

Virty [35]

Answer:

The heat of the reaction = -1985 J = -1.985 kJ

The enthalpy of the reaction is -39.7 kJ/ mol

Explanation:

Step 1: Data given

Volume of HCl = 100 mL the heat of the reaction = 0.1 L

Molarity of HCl solution = 0.500 M

Volume of KOH = 100 mL = 0.1 L

Molarity of KOH solution = 0.500 M

Initial temperature = 23.0 °C

Final temperature = 25.5 °C

Specific heat of the solution = 3.97 J/°C *g

Density of the solution = 1g/ mL

Step 2: Calculate heat

Q = m*c*ΔT

with m = the mass of both solution : 100g + 100 g ( since density = 1g/mL) = 200 g

c = the specific heat = 3.97 J/°C*g

ΔT = T2 -T1 = 25.5 = 23 = 2.5 °C

Q = 200g *3.97 J/°C*g * 2.5°C = 1985 J (= -1985 J because it's exothermic)

Step 3: Calculate the number of moles

Number of moles = Molarity * Volume

Number of moles = 0.5 * 0.1 L = 0.05 moles

(Moles of the acid are equal to the moles of water produced.

Moles of solution = 0.05 moles)

Step 4: Calculate the enthalpy of the reaction

ΔH = heat change /Number of moles

= -1.985 kJ/ 0.05 moles

=- 39700 J/mol = -39.7 kJ/ mol

The enthalpy of the reaction is -39.7 kJ/ mol

The enthalpy of the reaction is negative, this means the reaction is exothermic ( which means the final temperature is higher than the initial temperature.)

7 0

3 years ago

An unknown gas is found to diffuse through a porous membrane 4.11 times more slowly than h2 what is the molecular weight of the

kirill [66]

To answer this question, you need to know Graham's Law of Effusion/Diffusion formula. In this formula, the rate of diffusion/effusion would be influenced by the mass. As the molecule has bigger mass, the rate should be slower because it will be harder to pass the membrane. The calculation should be:
Rate 1 / Rate 2 = √[M2/M1]
4.11/1= √[M2/2]
M2=33.78 g/mol

5 0

3 years ago

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Which of the following is a reason to make an armature the parent of a creature

REY [17]

you have to show us the rest of it because we have no idea what your looking at. I'm sorry

3 0

3 years ago

Electrons in atoms exist in particular energy level. A ___ must be emitted or absorbed to move between energy levels.

svetlana [45]

Answer:

Photon of light

Explanation:

According to Bohr's model of the atom, electrons in atoms are found in specific energy levels. These energy levels are called stationary states, an electrons does not radiate energy when it occupies any of these stationary states.

However, an electron may absorb energy and move from one energy level or stationary state to another. The energy difference between the two energy levels must correspond to the energy of the photon of light absorbed in order to make the transition possible.

Since electrons are generally unstable in excited states, the electron quickly jumps back to ground states and emits the excess energy absorbed. The frequency or wavelength of the emitted photon can now be measured and used to characterize the transition. This is the principle behind many spectrometric and spectrophotometric methods.

8 0

3 years ago

What is the percent of Cr in Cr2O3

IgorLugansk [536]

The percentage of Chromium in Chromium Oxide is calculated as follow,

Step 1:
Calculate Molar mass of Cr₂O₃,
Cr = 51.99 u
O = 16 u
So,
2(51.99) + 3(16) = 103.98 + 48 = 151.98 u

Step 2:
Secondly divide molar mass of only chromium with total mass of Cr₂O₃ and multiply with 100.
i.e.
= $\frac{103.98}{151.98}$ × 100

= 68.41 %
So, the %age composition of chromium in chromium oxide is 68.41 %.

5 0

3 years ago

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