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2 years ago

The correct mass of a block is 28.0 grams. A chemist measures the block

Chemistry

1 answer:

Sati [7]2 years ago

3 0

Answer: NOT accurate, but precise.

[translation: You screwed up, but did it in style].

Explanation:

The average mass measurement is 41.95g. Compared to the actual value of 28.0 grams, the measurement is NOT accurate.

The standard deviation for the data is 0.112. Dependiong on your definition of precision, this looks relatively good. I would go for precise.

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When aqueous solutions of NH4OH(aq) and CuCl2(aq) are mixed, the products are NH4Cl(aq) and Cu(OH)2(s). What is the net ionic eq

Ilia_Sergeevich [38]

Answer:

2OH^-(aq) + Cu^2+(aq) -----> Cu(OH)2(s)

Explanation:

The net ionic equation usually shows the main ionic reaction that goes in the system. The other ions that do not participate in this net ionic equation are called spectator ions. Spectator ions do not participate in the main reaction occurring in the system.

The net ionic equation quite often result in the formation of a solid precipitate in the system such as Cu(OH)2.

The net ionic equation for this reaction is;

2OH^-(aq) + Cu^2+(aq) -----> Cu(OH)2(s)

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3 years ago

Is the equation balanced or unbalanced? Explain. AI + O2 --> AI2O3

anastassius [24]

Answer:

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2 years ago

Use the given data at 500 K to calculate ΔG°for the reaction

Anton [14]

Answer : The value of $\Delta G^o$ for the reaction is -959.1 kJ

Explanation :

The given balanced chemical reaction is,

$2H_2S(g)+3O_2(g)\rightarrow 2H_2O(g)+2SO_2(g)$

First we have to calculate the enthalpy of reaction $(\Delta H^o)$ .

$\Delta H^o=H_f_{product}-H_f_{reactant}$

$\Delta H^o=[n_{H_2O}\times \Delta H_f^0_{(H_2O)}+n_{SO_2}\times \Delta H_f^0_{(SO_2)}]-[n_{H_2S}\times \Delta H_f^0_{(H_2S)}+n_{O_2}\times \Delta H_f^0_{(O_2)}]$

where,

$\Delta H^o$ = enthalpy of reaction = ?

n = number of moles

$\Delta H_f^0$ = standard enthalpy of formation

Now put all the given values in this expression, we get:

$\Delta H^o=[2mole\times (-242kJ/mol)+2mole\times (-296.8kJ/mol)}]-[2mole\times (-21kJ/mol)+3mole\times (0kJ/mol)]$

$\Delta H^o=-1035.6kJ=-1035600J$

conversion used : (1 kJ = 1000 J)

Now we have to calculate the entropy of reaction $(\Delta S^o)$ .

$\Delta S^o=S_f_{product}-S_f_{reactant}$

$\Delta S^o=[n_{H_2O}\times \Delta S_f^0_{(H_2O)}+n_{SO_2}\times \Delta S_f^0_{(SO_2)}]-[n_{H_2S}\times \Delta S_f^0_{(H_2S)}+n_{O_2}\times \Delta S_f^0_{(O_2)}]$

where,

$\Delta S^o$ = entropy of reaction = ?

n = number of moles

$\Delta S_f^0$ = standard entropy of formation

Now put all the given values in this expression, we get:

$\Delta S^o=[2mole\times (189J/K.mol)+2mole\times (248J/K.mol)}]-[2mole\times (206J/K.mol)+3mole\times (205J/K.mol)]$

$\Delta S^o=-153J/K$

Now we have to calculate the Gibbs free energy of reaction $(\Delta G^o)$ .

As we know that,

$\Delta G^o=\Delta H^o-T\Delta S^o$

At room temperature, the temperature is 500 K.

$\Delta G^o=(-1035600J)-(500K\times -153J/K)$

$\Delta G^o=-959100J=-959.1kJ$

Therefore, the value of $\Delta G^o$ for the reaction is -959.1 kJ

3 0

2 years ago

Hello, a little help please guys:( Explain how the series of experiments performed by Crookes, Thomson, Rutherford, and Chadwick

White raven [17]

I did some investigation and summarized the process and made a clearer explanation so those who are confused can imagine the process better :) A scientific theory attempts to explain and describe why things happen. Hypotheses are formed and experiments are done to validate or toss the hypothesis based on the data collected. The Atomic Theory has gone through lots of refining as a scientific theory. For instance, William Crookes conduced an experiment with cathode ray tubes powered by electricity that glowed when powered. Crookes placed an object in between the positive and negative electrode and concluded that the shadow made on the positive side was small particles of matter traveling from the negative side. But more evidence was needed so, later on, J.J. Thomson continued Crookes experiment. He tested what would happen if a negative or positive charged rod was placed along the ray tubes and if it would differ if a different element was used as the negative electrode. Thomson found out that the beam had negatively charged particles and that even if the negative electrode is substituted, the glow is still present, meaning that all elements also had the small negative particles. These particles(now known as electrons) were smaller than the atom and were added to the model of the atom dispersed throughout the neutrally charged atom inside its positive sphere. Now came along Rutherford hoping to support Thomsons model by firing positively charged particles at a thin gold foil thinking it would go straight through the foil, but instead it evenly distributed as they went through the foil, concluding that atoms have a small, dense nucleus(containing positive protons and most of the mass of the atom) that deflected the particles passing through. This was a drastic change in the model now knowing that 1 proton has 2000 times the mass of an electron, but its positive charge cancels the negative electron. After WW1, Chadwick and others were seeing that sometimes the mass of the atom was greater than the mass of the protons and the number of protons was less than the mass of the atom. So it was thought that there were extra electrons and protons adding mass in the nucleus but cancelling their charges, but Rutherford proposed a particle with mass but no charge and called it a neutron; made of paired protons and electrons. But scientists kept studying atoms since there was no evidence of the neutron. Chadwick repeated these experiments though, in hopes to find the neutron and succeeded in 1932, finding it in the nucleus with a close mass to the proton. Thanks to these experiments for refining a scientific theory, we now have a clearer model of the atom.

7 0

2 years ago

Define natural gas, liquefied petroleum gas (LPG), and liquefied natural gas (LNG). What three countries have most of the world’

mrs_skeptik [129]

Answer:

The answer is treated below.

Explanation:

Natural gas: Natural gas is not used in its pure form; it is processed and converted into cleaner fuel for consumption. It is a fossil fuel composed almost entirely of methane, but contain small amounts of other gases, including ethane, propane, pentane and butane. It is a combustible, gaseous mixture of simple hydrocarbon compounds, usually found in deep underground reservoirs formed by porous rock. Natural gas is mainly used as fuel for generating heat and electricity.

Liquefied petroleum gas (LPG): Liquefied Petroleum Gas is a byproduct of natural gas and oil extraction and crude oil refining . At room temperature, liquefied petroleum gas is a colourless and odourless gas which consists generally of butane (C4H10) or propane (C3H8) or a mixture of both.

Liquefied natural gas (LNG): Is natural gas that has been liquefied for ease of transport or storage. It is refrigerated to a very low temperature (-162 Celsius). At this temperature it becomes an odourless, non-toxic liquid that can be safely transported over long distances.

Three countries that have most of the world’s natural gas reserves

Russia
Iran
Qatar

Major advantages of using conventional natural gas as an energy resource:

It is less expensive when compared to other fossil fuels.
It is safer and easier to store when compared to other fossil fuels

Major disadvantages of using conventional natural gas as an energy resource:

It costs more to recover the remaining natural gas because of flow, access, etc.
It is not a renewable source.
it is a combustible material, It must be handled with care.
It does not contribute to greenhouse gases.

Three sources of unconventional natural gas :

Tight Gas
Shale Gas
Coalbed Methane

Major problems related to the use of Tight Gas

When Hydrofluoric acid is used to release tight gas in reserves it potentially an issue simply because the substance is so dangerous. A spill or a leak could harm workers and pollute groundwater for uses.

Major problems related to the use of Shale Gas

Risk of ground and surface water contamination.
Have impacts on air quality.

Major problems related to the use of Coalbed Methane

The development of coalbed methane will result to soil disturbance from construction of wells, roads, and the associated pipeline and electric power rights-of-ways.
It has impact on wildlife.

8 0

3 years ago