The process of change in a population over time is called what?

Which refers to the distance between two crests or two troughs on a transverse wave?

Oksanka [162]

Answer:

amplitude is the answer.

6 0

2 years ago

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State the five the five basic assumptions of the kinetic-molecular theory.

Ivan

Answer:

The primary assumptions are as follows:

Any gas is a collection of innumerable number of minuscule particles which are known as molecules according to Avogadro’s law.

There are no forces of attraction or repulsion among the particles or between the molecules and the surroundings.

The gas particles are always at straight, rapid, fast & random motion resulting in inevitable collisions with other particles and the surroundings that changes direction of motion.

Since the particle are spherical, solid and elastic the collisions involving them are elastic in nature as well i.e their kinetic energy is conserved even after collisions.

The total kinetic energy of the particles is proportional to the absolute temperature.

In some books two other assumptions are given as well:

1. The size or area of each particle is negligible compared to that of the container.

2. Pressure of gas is result of the continuous clash of the particles with the wall of the container.

or

The simplest kinetic model is based on the assumptions that: (1) the gas is composed of a large number of identical molecules moving in random directions, separated by distances that are large compared with their size; (2) the molecules undergo perfectly elastic collisions (no energy loss) with each other and with the walls of the container, but otherwise do not interact; and (3) the transfer of kinetic energy between molecules is heat. These simplifying assumptions bring the characteristics of gases within the range of mathematical treatment.

Such a model describes a perfect gas and is a reasonable approximation to a real gas, particularly in the limit of extreme dilution and high temperature. Such a simplified description, however, is not sufficiently precise to account for the behaviour of gases at high densities.

Based on the kinetic theory, pressure on the container walls can be quantitatively attributed to random collisions of molecules the average energy of which depends upon the gas temperature. The gas pressure can therefore be related directly to temperature and density. Many other gross properties of the gas can be derived, such as viscosity, thermal and electrical conductivity, diffusion, heat capacity, and mobility. In order to explain observed deviations from perfect gas behaviour, such as condensation, the assumptions must be appropriately modified. In doing so, considerable insight has been gained as to the nature of molecular dynamics and interactions.

7 0

2 years ago

What mass of H2 is needed to react with 8.75 g of O2 according to the following equation: O2(g) + H2(g) → H2O(g)?

Alika [10]

Answer:- B: $1.10g H_2$ is the right answer.

Solution:- The balanced equation is:

$O_2(g)+2H_2(g)\rightarrow 2H_2O(g)$

We have been given with 8.75 grams of oxygen and asked to calculate the grams of hydrogen needed to react with given grams of oxygen according to the balanced equation.

From balanced equation, 1 mole of oxygen reacts with 2 moles of hydrogen.

So, let's convert grams of oxygen to moles and multiply it by the mole ratio to calculate the moles of hydrogen that are easily converted to grams on multiplying by it's molar mass.

The complete set up looks as:

$8.75g O_2(\frac{1mole}{32g})(\frac{2mole H_2}{1mole O_2})(\frac{2.02g}{1mole})$

= $1.10g H_2$

Hence, the right option is B: $1.10g H_2$ .

7 0

3 years ago

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What should be the temperature of the solvent before adding it to the sample to be recrystallized?

Serhud [2]

Answer:

Near the boiling point of the solvent

Explanation:

The process of recrystallization is hinged on the fact that the amount of solute that can be dissolved by a solvent increases with temperature. The process involves creation of a solution by dissolving a solute in a solvent at or near its boiling point. At the boiling point of the solvent, the solute has a greater solubility in the solvent; not much volume of the hot solvent is required to dissolve the solute.

Before the solution is later cooled, you can now filter out insoluble impurities from the hot solvent. The quantity of the original solute drops appreciably because impurities have been removed. At this lower temperature, the solution becomes saturated and the solute can no longer be held in solution hence it forms pure crystals of solute, which can be recovered.

Recrystallization must be carried out using the proper solvent. The solute must be relatively insoluble in the solvent at room temperature but more soluble in the solvent at elevated temperature.

3 0

2 years ago

How many moles of hydrogen gas will be produced if 5.00 moles of zinc reactions with an excess amount of sulfuric acid

harkovskaia [24]

Answer:

Moles of Hydrogen produced is 5 moles

Explanation:

The balanced Chemical equation for reaction between zinc and sulfuric acid is :

$Zn(s) + H_{2}SO_{4}(aq) \rightarrow ZnSO_{4}(aq) + H_{2}(g)$

This equation tells that ; when 1 mole of Zn react with 1 mole of sulfuric acid, it produces 1 mole of zinc sulfate and 1 mole of hydrogen.

Since sulfuric acid is in excess so Zinc is the limiting reagent

(Limiting reagent : Substance which get consumed when the reaction completes, limiting reagent helps in predicting the amount of products formed)

Limiting reagent (Zn) will decide the amount of Hydrogen produced

$Zn(s) + H_{2}SO_{4}(aq) \rightarrow ZnSO_{4}(aq) + H_{2}(g)$

$1\ mole\ zinc\rightarrow 1\ mole\ H_{2}$

So,

$5\ mole\ zinc\rightarrow 5\ mole\ H_{2}$

Hence moles of Hydrogen produced is 5 moles

3 0

2 years ago