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2 years ago

What is an atom in chemistry

Chemistry

2 answers:

tamaranim1 [39]2 years ago

8 0

And atom is the smallest unit of matter

oksano4ka [1.4K]2 years ago

6 0

Answer:

Explanation:

An atom is the smallest unit of matter that has the properties of an element. It is composed of a dense core called the nucleus and a series of outer shells occupied by orbiting electrons.

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Ethylene oxide (EO) is prepared by the vapor-phase oxidation of ethylene. Its main uses are in the preparation of the antifreeze

Rashid [163]

Answer:

a. Δ $H^0_{rxn} = -108.0\frac{kJ}{mol}$

b. 320.76° C

Explanation:

a.)

we can solve this type of question (i.e calculate Δ $H^0_{rxn}$ , for the gas-phase reaction ) using the Hess's Law.

Δ $H^0_{rxn}$ = $E_{product} deltaH^0_{t}-E_{reactant} deltaH^0_{t}$

Given from the question, the table below shows the corresponding Δ $H^0_{t}(kJ/mol)$ for each compound.

Compound $H^0_{t}(kJ/mol)$

Liquid EO -77.4

$CH_4_(g_)$ -74.9

$CO_(g_)$ -110.5

If we incorporate our data into the above previous equation; we have:

Δ $H^0_{rxn}$ = (-110.5 kJ/mol + (-74.9 kJ/mol) ) - (-77.4 kJ/mol)

= $-108.0 \frac{kJ}{mol}$

b.)

We are to find the final temperature if the average specific heat capacity of the products is 2.5 J/g°C

Given that:

the specific heat capacity (c) = 2.5 J/g°C

$T_{initial}$ = 93.0°C &

the enthalpy of vaporization (Δ $H^0_{vap}$ ) = 569.4 J/g

If, we recall; we will remember that; Specific Heat Capacity is the amount of heat needed to raise the temperature of one gram of a substance by one kelvin.

∴ the specific heat capacity (c) is given as = $\frac{Heat(q)}{mass*changeintemperature(T_{initial}-T_{final})}$

Let's not forget as well, that Δ $H^0_{vap}$ = $\frac{q}{mass}$

If we substitute Δ $H^0_{vap}$ for $\frac{q}{mass}$ in the above equation, we have;

specific heat capacity (c) = $\frac{deltaH^0_{vap}}{T_{final}-T_{initial}}$

Making ( $T_{final}- T_{initial}$ ) the subject of the formula; we have:

$T_{final}- T_{initial}$ = $\frac{delat H^0_{vap}}{specificheat capacity}$

$(T_{final}-93.0^0C)=\frac{569.4J/g}{2.5J/g^0C}$

$T_{final}=\frac{569.4J/g}{2.5J/g^0C}+93.0^0C$

= 227.76°C +93.0°C

= 320.76°C

∴ we can thereby conclude that the final temperature = 320.76°C

7 0

3 years ago

How many significant figures<br> are in this number?<br> 0.00708900

Norma-Jean [14]

Don’t know sorry 1.627

4 0

3 years ago

Read 2 more answers

When the surface water temperature is still well below the water boiling temperature, some bubbles at the bottom tend to float u

irga5000 [103]

Answer:

The reasons why the seemingly floating bubbles disappear was that they tend to loss their latent heat to the water molecules at the surface water.

Explanation:

Heat energy has a considerable effect on the velocity of molecules including water. The water molecules below the container will receive much more heat energy than those above it. This heat energy in the form of specific heat capacity and latent heat that result in the increase in the speed of individual molecules of water and finally to the escape of the molecules to a colder region of the container, in this case the upper region. At the collision of the bottom water to the surface water, they tend to exchange their heat content, the hotter molecules will lose their heat to the cold ones. When the formerly hot molecules encounter this, it will result in lowering the temperature and consequentially to the reduction of their movement, once in the form of bubble, now become ordinary water. This convectional transfer of heat energy will continue until the whole system has a uniform temperature depending on the consistency of the heat source.

7 0

3 years ago

Consider the unbalanced equation for the oxidation of aluminum.

SashulF [63]

In order to balance an equation, we apply the principle of conservation of mass, which states that mass can neither be created nor destroyed. Therefore, the mass of an element before and after a reaction remains constant. Here, the balanced equation becomes:
4Al + 3O₂ → 2Al₂O₃

The coefficients are 4, 3 and 2.

8 0

2 years ago

Read 2 more answers

Match the following items. Match the items in the left column to the items in the right column. 1. general or nonspecific observ

ivann1987 [24]

when column B is like the attached pic: (missing in your question)

so the matches will be like that:

1- Qualitative :

as Qualitative is a general or nonspecific observation, they also don't require

measurements and even can't be measured, that is because of the reality is

being approximated only. It describes qualities and uses opinion

2- Hypothesis :

as a hypothesis is an educated guess quantitative, and it is a prediction stated

in " If and then " form. a hypothesis to be valid need a research such as:

-Encyclopedia & state and local research facilities & scientific journals.

3- Direct relationship:

as a Direct relationship is when two variable change in the same direction,

and one remaining larger than the other by the same factory.

- this is a type of a relationship in which there is a change with one variable, and corresponding with the change in the other. and because this corresponding change with the other variable in the same direction so it refers to a positive relationship.

4- Quantitative:

as Quantitative is a measured observation, It's an information or data based

on quantities obtained. And using numbers, equipment and standard units.

5- Control :

as control is standard, reference data or experiment qualitatively. this is what

you compare your experimental results to. This is for comparing results, it

used as a standard for comparison and use baseline measurements to use in

the comparing.

6- Theory :

as Theory is a presently accepted explanation of how something happened.

Scientifically acceptable general principles to explain phenomena. It the

general or abstract principles of the science. for example the wave theory of

light.

7- Law :

as a law is a statement that explains what something does under the same

conditions. when we take about law in science, it is a general rule to explain

the observations in the form of a mathematical statement. Scientific law may

be stated in words or expressed as a mathematical equations.

8- Best fit curve:

as best fit curve is a curve drawn to average the data's deviations direct

relationship. It is a process of constructing a curve that has best fit to a

series of data points.

7 0

3 years ago

What is an atom in chemistry​

What is an atom in chemistry