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1
a
C
Copper(II) nitrate decomposes on heating. The reaction is endothermic.
2Cu(NO),(s) → 2CuO(s) + 4NO2(g) + 0,(9)
Sketch a reaction pathway diagram for this reaction to include the
activation energy
[3]
b Draw an energy cycle to calculate the standard enthalpy change for
this reaction, using enthalpy changes of formation.
[3]
Calculate the enthalpy change for this reaction using the following
enthalpy changes of formation.
AH, [Cu(NO, ),(s)] = -302.9 kJ mol-'
AH, [CuO(s)] =-157.3 kJ mol-!
AH [NO,(g)] = +33.2 kJ mol-!
[3]
d Copper(II) sulfate is soluble in water. A student dissolved 25.0 g of
copper(II) sulfate in 100 cm of water in a polystyrene beaker stirring
all the time. The temperature of the water fell by 2.9 °C.
i Calculate the enthalpy change of solution of copper(II) sulfate.
(specific heat capacity of water = 4.18 Jg1 °C ; relative
molecular mass of copper(II) sulfate = 249.7 g mol-')
[3]
ii Suggest one source of error in this experiment and explain how
the error affects the results.
[2]
[Total: 14]

Answer:

Q = mcT ...you can either substitute the molar heat capacity of water in the place of c or the specific heat capacity of water.

Explanation:

Answer:

The awnser is Ionic bond

The total charge on an atom comes from protons and electrons.

The proton is positively charged while the electron is negatively charged. A neutral atom would have an equal number of protons and electrons.

An atom with more protons than electrons will be positively charged while those with more electrons than protons will be negatively charged.

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Georgia needs evidence

Answer:

B

Explanation:

Answer:

he presence of nucleus which contains genetic material and is enclosed by a nuclear membrane sets them apart from prokaryotic cells. All complex organisms are eukaryotic and they reproduce by mitosis or meiosis. Eukaryotic cells are typically much larger than those of prokaryotes.

Explanation:

Answer:

Explanation:

The balanced equation says that we'll get 1 mole of H2 for every 1 mole of Mg.  50 grams of H is 50g/2 g/mole = 25 moles of H2.  That means we'll need 25 moles of Mg.  Convert that into grams:  (25 moles Mg)*(24.3 g/mole) = 607 grams Mg.  

At STP, all gases occupy 22.4 liters/miole.  That means 25 moles of H2 would occupy (25 moles)*(22.4 liters/mole) = 560 liters.

We know that water is tasteless, odorless, and transparent. In small quantities, it is also colorless. However, when a large amount of water is observed, as in a lake or the ocean, it is actually light blue in color. The blue hue of water is an intrinsic property and is caused by selective absorption and scattering of white light. These and other properties of water depend on its chemical structure.The transparency of water is important for organisms that live in water. Because water is transparent, sunlight can pass through it. Sunlight is needed by water plants and other water organisms for photosynthesis.Chemical Structure of WaterEach molecule of water consists of one atom of oxygen and two atoms of hydrogen, so it has the chemical formula H2O. The arrangement of atoms in a water molecule explains many of water’s chemical properties. In each water molecule, the nucleus of the oxygen atom (with 8 positively charged protons) attracts electrons much more strongly than do the hydrogen nuclei (with only one positively charged proton). This results in a negative electrical charge near the oxygen atom (due to the "pull" of the negatively charged electrons toward the oxygen nucleus) and a positive electrical charge near the hydrogen atoms. A difference in electrical charge between different parts of a molecule is called polarity. A polar molecule is a molecule in which part of the molecule is positively charged and part of the molecule is negatively charged.

•Hydrogen Bonding-

Opposite electrical charges attract one another. Therefore, the positive part of one water molecule is attracted to the negative parts of other water molecules. Because of this attraction, bonds form between hydrogen and oxygen atoms of adjacent water molecules. This type of bond always involves a hydrogen atom, so it is called a hydrogen bond. Hydrogen bonds are bonds between molecules, and they are not as strong as bonds within molecules. Nonetheless, they help hold water molecules together.

•Sticky, Wet Water-

Water has some unusual properties due to its hydrogen bonds. One property is cohesion, the tendency for water molecules to stick together. The cohesive forces between water molecules are responsible for the phenomenon known as surface tension. The molecules at the surface do not have other like molecules on all sides of them and consequently they cohere more strongly to those directly associated with them on the surface. For example, if you drop a tiny amount of water onto a very smooth surface, the water molecules will stick together and form a droplet, rather than spread out over the surface. The same thing happens when water slowly drips from a leaky faucet. The water doesn't fall from the faucet as individual water molecules but as droplets of water.

•Density of Ice and Water-

The melting point of water is 0°C. Below this temperature, water is a solid (ice). Unlike most chemical substances, water in a solid state has a lower density than water in a liquid state. This is because water expands when it freezes. Again, hydrogen bonding is the reason. Hydrogen bonds cause water molecules to line up less efficiently in ice than in liquid water. As a result, water molecules are spaced farther apart in ice, giving ice a lower density than liquid water. A substance with lower density floats on a substance with higher density. This explains why ice floats on liquid water, whereas many other solids sink to the bottom of liquid water.In a large body of water, such as a lake or the ocean, the water with the greatest density always sinks to the bottom. Water is most dense at about 4°C. As a result, the water at the bottom of a lake or the ocean usually has temperature of about 4°C. In climates with cold winters, this layer of 4°C water insulates the bottom of a lake from freezing temperatures. Lake organisms such as fish can survive the winter by staying in this cold, but unfrozen, water at the bottom of the lake.

Hope it helps

Considering the definition of ionization energy, the highest ionization energy belongs to the element:

a. Be

b. Ar

c. Cl

Electrons are held in atoms by their attraction to the nucleus, which means that energy is needed to remove an electron from the atom.

You should keep in mind that the electrons of the last layer are always lost, because they are the weakest attracted to the nucleus.

Ionization energy, also called ionization potential, is the necessary energy that must be supplied to a neutral, gaseous, ground-state atom to remove an electron from an atom. When an electron is removed from a neutral atom, a cation with a charge equal to +1 is formed.

In a group, the ionization energy increases upwards because when passing from one element to the bottom, it contains one more layer of electrons. Therefore, the valence layer electrons, being further away from the nucleus, will be less attracted to it and it will cost less energy to pluck them.

In the same period, in general, it increases as you shift to the right. This is because the elements in this way have a tendency to gain electrons and therefore it will cost much more to tear them off than those on the left which, having few electrons in the last layer will cost them much less to lose them.

Considering all the above, from each of the pairs, the highest ionization energy belongs to the element:

a. Be

b. Ar

c. Cl

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Answer: o.125 moles of gas X with a molar mass of 240

Explanation:

2.8 dm3 of gas X at STP has equal mass with 11.2 dm3 of C2H6 at STP. What is the number of mole if gas X has 30 grams?

the molar volume of any gas at STP is the volume of 1 mole at STP

and is 22.4 L

the C2H6 has a volume of 11.2L at STP so it has 0.5 moles

C2H6 has a molar mass of (2 X 12) +(6 X 1) = 24 + 6 = 30

0,5 moles weighs 15 gm at STP with

so 15 gm at STP with 2.8 L for gas X

PV=nRT

P=1 atm

T =273.2k

V =2.8

R =0.082

n = PV/RT = (1 X 2.8)/(0.082 X 273.2) =0.125 moles of gasX

the weight of gas X is 30 gms

so 30/.125 =240 g/mole = molar mass of gas X

An H atom is made up of a nucleus with a +1 charge, as well as a single electron. Therefore, the only positively charged ion possible has charge +1.

I hope this helps!

The amount, in grams, of water, that the student originally started with would be 252 g

From the balanced equation of the reaction, the ratio of H2O to H2 is 1:1. Thus for every 1 mole of water that is separated, 1 mole of H2 is produced.

Recall that: mole = mass/molar mass

Mole of 28.0 g H2 produced = 28/2

                                              = 14 moles

Equivalent mole of H2O would, therefore, be 14 moles.

Mass of 14 moles H2O = mole x molar mass

                                      = 14 x 18

                                      = 252 g

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Answer:

Box#:

1:CoS

2:Co2S3

3:CoSO4

4:Co2(SO4)3

5:CoSO3

6:Co2(SO3)3

Explanation:

1:Co(II) is -2 and S is -2, so the charges cancel

2:Co(III) is -3 and is -2, so you cross the charges but do not reduce

3:Co(II) is -2 and SO4 is -2, so the charges cancel

4:Co(III) is -3 and SO4 is -2 so the charges cross but do not reduce

5:Co(II) is -2 and SO3 is -2 so the charges cancel

6:Co(III) is -3 and SO3 is -2 so the charges once again cross

Answer:

Cobalt (II) sulfide → CoS

Cobalt (III) sulfide → Co₂S₃

Cobalt (II) sulfate → CoSO₄

Cobalt (III) sulfate → Co₂(SO₄)₃

Cobalt (II) sulfite → CoSO₃

Cobalt (III) sulfite → Co₂(SO₃)₃

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When the mixture of ions undergoes electrolysis, Br- is most easily oxidized.

Electrolysis refers to the decomposition of a solution by the passage of direct current through it. During electrolysis, a specie is oxidized and another specie is reduced since it is a redox reaction.

Among all the ions; Mg2+ , Cu2+ ,F-, Cl-, Br-, the ion that is most easily oxidized in Br- which is oxidized to Br2.

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Answer:

[Xe] 6s2

Explanation:

hope it helps Electron configuration

Answer:

Explanation:

Pencils are though formed of wood that acts as a bad conductor of electricity, quite strangely pencils can be electrically charged.

Here pencils have non-metal carbons present in its graphite tip and this makes the pencils charged.

When this pencil is held near the water of the tap, the hydrogen ions get attracted and thereby the water gets attracted to the pencil.

Water, however, is an excellent conductor of electricity and therefore water and electricity are a dangerous combination.

Answer:

[tex]\implies \sf D = \dfrac{PM}{RT}[/tex]

[tex]\implies \sf 3.35= \dfrac{1 \times M}{ \frac{1}{12} \times 298}[/tex]

[tex]\implies \sf 3.35= \dfrac{12\times M}{ 298}[/tex]

[tex]\implies \sf 3.35 \times 298= 12\times M[/tex]

[tex]\implies \sf 998.3= 12\times M[/tex]

[tex]\implies \sf M = \dfrac{998.3}{12} [/tex]

[tex]\implies \bf M = 83.1917 \: \frac{g}{mol} [/tex]

Answer:

Ionic bonds result from the transfer of electrons from one atom to another

Explanation:

In covalent bonds, atoms share electrons, whereas in ionic bonds atoms transfer electrons. The reaction components of covalent bonds are electrically neutral, whereas for ionic bonds they are both charged.Covalent bonds are formed between two non-metals, whereas ionic bonds are formed between a metal and non-metal.  

Answer:

Covalent bonds are defined as sharing of electrons, ionic bonds are the result of transferred electrons;

Covalent bonds form between non-metals (elements) and ionic bonds form between metal and non-metals (ions)

Answer:

The warmer the water gets the particles begin to expand and starts vibrating

Answer:

1:

•a typical metal tends to have a higher melting and boiling point than a typical non metal which has a low melting and boiling point

•a typical metal tends to have a shiny appearance than a typical non metal which has a dull apearance

•and finally, a typical metal is a good conductor of electricity and heat while a typical non metal isn't

2:

elements E and C

3:

a, it doesn't conduct electricity

b, it's a good conductor of heat/ has a high melting point/ has a high boiling point (you can choose either that sits right with you)

Answer:

Protons are positively charged. The mass is slightly lower than a neutron.The location of a proton is nucleus. The the role of a proton is to help bind the nucleus together.

Explanation:

n-propylbenzene will travel the largest distance because it interacts most effectively with the stationary phase followed by phenol and benzoic acid will travel the least distance because it interacts poorly with the mobile phase.

Thin layer chromatography involves the separation of a mixture using a stationary phase made of  silica gel on a glass plate and an appropriate mobile phase. The extent of separation is highly dependent on the magnitude of interaction between the solute and the mobile phase. and stationary phase.

The first step in thin layer chromatography is to make a thin mark at the bottom portion of the plate then spot the plate with the sample. The mobile phase is now introduced into the TLC chamber a little below the mark. The plate is now placed in the stationary phase such that the mark is above the solvent level.

The TLC chamber is now covered and enough time is allowed for separation to occur. The spots can be seen using a suitable indicator dye or with a the aid of UV light

After the  separation of a homogeneous, liquid mixture containing benzoic acid, n-propylbenzene, and phenol, provided a 4:1 hexane to ethyl acetate solution as the eluent, we can see that n-propylbenzene will travel the largest distance because it interacts most effectively with the stationary phase followed by phenol and benzoic acid will travel the least distance because it interacts poorly with the mobile phase.

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Answer:

They cannot be broken down any further

Explanation:

An element is a substance that cannot be broken down into a simpler format. They are distinguished by a unique atomic number. The elements are organized by their atomic number in the periodic table, which highlights elements with similar properties.

Answer: Na2SO4

The molecular formula for sodium sulphur and oxygen​ is: (Na2SO4)

,  Hope this helps :)

Have a great day!!

Answer:

the same number of atomic orbitals.

Explanation:

Answer:

All of the elements in a period have the same number of atomic orbitals. For example, every element in the top row (the first period) has one orbital for its electrons. All of the elements in the second row (the second period) have two orbitals for their electrons.

hope this helps

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Answer:

A calculated field will appear in the field list window, but will not take up space in the source data. In the example shown, a calculated field called "Unit Price" has been created with a formula that divides Sales by Quantity. The pivot table displays the calculated unit price for each product in the source data.

Explanation:

The PivotTable Field List contains calculated fields. Items from other fields that have been calculated display as items.

Calculated fields are defined as the fields whose values are determined by other fields' values and perhaps external sources. Data from other fields can be calculated using calculated fields. Calculating the sum of two fields is a simple example, but more complicated calculations, such averaging values from multiple tables or even gaining access to external data, are theoretically feasible.

PivotTable Field List is defined as the Areas part of the Field List allows you to organize the fields wherever you like. It features a field section where you select the fields you wish to display in your PivotTable. Using a pivot table is an interactive method for quickly summarizing enormous amounts of data.

Thus, the PivotTable Field List contains calculated fields. Items from other fields that have been calculated display as items.

To learn more about calculated fields, refer to the link below:

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