A tablespoon of very hot water is added to a pint of very cold water. What will happen to the temperature of the water?

Explain how the understanding of atomic emission spectrum lead to development of the atomic theory

kiruha [24]

here we have to explain the development of the atomic theory by the atomic emission spectrum.

The most important aid in determining the structure of an atom has been study of radiation emitted and absorbed by the elements. The glowing atoms of an element emit radiations.

These are called the atomic spectra. This study helped to understand the structure of the atoms.

To explain the atomic spectra the Bohr's model was introduced. The postulates of the Bohr's model explain the fine spectrum of the atom up to the particle nature of the electrons.

Later some modification on the Bohr's postulates was made to explain the wave nature of the electrons as well. But the atomic spectra is best be understood by the Bohr's atomic model which developed the atomic theory.

Thus the understanding of emission spectrum of atom to develop the atomic theory is explained.

8 0

4 years ago

What volume of carbon dioxide will be produced if 2. 90 moles of iron (fe) is produced?

AlexFokin [52]

The volume of carbon dioxide that will be produced is 191.4 g.

Calculation:

The following is the balanced equation for the given reaction:

Fe₂O₃(s) + 3CO(g) → 2Fe(s) + 3CO₂(g),

It is obvious that when 1.0 mole of Fe2O3 reacts with 3.0 mole of CO, 2.0 mole of Fe and 3.0 mole of CO2 are produced.

Hence by using cross multiplication:

If 2.0 mol of Fe was produced with → 3.0 mol of CO₂, from stoichiometry.

Then how many moles of CO₂ are produced by 2.9 mol of Fe?

To find the answer we have a formula:

∴ The no. of moles of CO₂ produced = (3.0 mol)(2.9 mol)/(2.0 mol) = 4.35 mol.

∴ The mass of CO₂ produced = no. of moles x molar mass = (4.35 mol)(44.0 g/mol) = 191.4 g.

Learn more about the balanced reaction here:

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6 0

2 years ago

What is the quantity of heat (in kJ) associated with cooling 185.5 g of water from 25.60°C to ice at -10.70°C?Heat Capacity of S

Cerrena [4.2K]

Taking into account the definition of calorimetry, sensible heat and latent heat, the amount of heat required is 37.88 kJ.

<h3>Calorimetry</h3>

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

<h3>Sensible heat</h3>

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

<h3>Latent heat</h3>

Latent heat is defined as the energy required by a quantity of substance to change state.

When this change consists of changing from a solid to a liquid phase, it is called heat of fusion and when the change occurs from a liquid to a gaseous state, it is called heat of vaporization.

<u><em>25.60 °C to 0 °C</em></u>

First of all, you should know that the freezing point of water is 0°C. That is, at 0°C, water freezes and turns into ice.

So, you must lower the temperature from 25.60°C (in liquid state) to 0°C, in order to supply heat without changing state (sensible heat).

The amount of heat a body receives or transmits is determined by:

Q = c× m× ΔT

where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

In this case, you know:

c= Heat Capacity of Liquid= 4.184 $\frac{J}{gC}$
m= 185.5 g
ΔT= Tfinal - Tinitial= 0 °C - 25.60 °C= - 25.6 °C

Replacing:

Q1= 4.184 $\frac{J}{gC}$ × 185.5 g× (- 25.6 °C)

Solving:

<u><em>Change of state</em></u>

The heat Q that is necessary to provide for a mass m of a certain substance to change phase is equal to

Q = m×L

where L is called the latent heat of the substance and depends on the type of phase change.

In this case, you know:

n= 185.5 grams× $\frac{1mol}{18 grams}$ = 10.30 moles, where 18 $\frac{g}{mol}$ is the molar mass of water, that is, the amount of mass that a substance contains in one mole.

ΔHfus= 6.01 $\frac{kJ}{mol}$

Replacing:

Q2= 10.30 moles×6.01 $\frac{kJ}{mol}$

Solving:

<u><em>0 °C to -10.70 °C</em></u>

Similar to sensible heat previously calculated, you know:

c = Heat Capacity of Solid = 2.092 $\frac{J}{gC}$
m= 185.5 g
ΔT= Tfinal - Tinitial= -10.70 °C - 0 °C= -10.70 °C

Replacing:

Q3= 2.092 $\frac{J}{gC}$ × 185.5 g× (-10.70) °C

Solving:

<h3>Total heat required</h3>

The total heat required is calculated as:

Total heat required= Q1 + Q2 +Q3

Total heat required=-19,868.98 J + 61,903 J -4,152.3062 J

<u><em>Total heat required= 37,881.7138 J= 37.8817138 kJ= 37.88 kJ</em></u>

In summary, the amount of heat required is 37.88 kJ.

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7 0

2 years ago

Explain why when a strong acid is titrated with a strong base, the pH at equivalence pt. is equal 7, while in the case of a weak

goldenfox [79]

Explanation:

The pH of a strong acid when titrated with a strong base is equal to 7 because of the formation of a neutral salt which corresponds to pH = 7.

But on the other hand,

The titration of the weak acid and strong base, the reaction taking place is:

HC₂H₃O₂ + OH⁻ ⇒ H₂O + C₂H₃O₂⁻

At the equivalence point, the pH is greater than 7 because of the conjugate base formed in the above reaction which gives OH⁻ in the solution as:

C₂H₃O₂⁻ + H₂O ⇒ HC₂H₃O₂ + OH⁻

<u>The hydroxide ions produced in the above reaction results in the pH above 7 (basic).</u>

5 0

3 years ago

230 cm3 of hot tea at 96 °C are poured into a very thin paper cup with 100 g of crushed ice at 0 °C. Calculate the final tempera

ivann1987 [24]

Answer:

Final temperature of the ice tea, x = 42.73°C

Explanation:

230 cm^3 = 230 g of liquid ( taking the density of tea as the same the density of water)

In cooling from 96°C to 0°

C (before freezing) the available energy is

96 × 230 = 22080 cal

The latent heat (the heat required to melt the crushed ice per gram) of fusion for water = 79.7 cal/g

Melting 100 g of crushed ice at 0°C will absorb

100 × 79.7 = 7970 cal

The retain heat of the iced Tea = (22080 - 7970) cal of heat raising the mixture temperature as follows

(22080 - 7970) = 14110 cal

The mass of the final solution 230 + 100 = 330 g solution

Final temperature = 14110 / 330 = 42.76°C

Or where specific heat of water = 4.186J/Kg°C

and the latent heat of the ice = 334J/Kg

We have

230 × (specific heat capacity of water) × (96 - x) =100× (specific heat capacity of water) ×(0-x) + (latent heat) ×100 =

230 × 4.186 × (96 - x) =100× 4.186 ×(x-0) + 100×334

1381.38×x = 59026.88

Final temperature of the ice tea, x = 42.73°C

5 0

3 years ago