A student knew that it was possible to make copper (II) sulphate crystals by adding copper (II)
carbonate to dilute sulphuric acid and warming the resulting solution to drive off some ofthe
water and then leaving the solution to crystallize. He decided to make copper (II) nitrate crystals
by similar method. The only change he made was to use dilute nitric acid. He left the final
solution for several days but failed to collect any crystals. Explain why the student did not get
any crystals to collect.
(10 marks)
Examiner: ProfM. K. Abekoe

Answer:

are called Compounds

Answer:

Compouds

think of a group

an they are alll combined

also "compounds" com-bind = com-POUNDS

Make's sense now?

The intermolecular forces or the strength of C is more than that of B.

What are intermolecular forces?

Here, we can see that C has dipole-dipole interaction while B has none.

Therefore, it states that the intermolecular forces present in C are much more than that in B.

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Answer:

a. BH₃

Explanation:

According to the octet rules, atoms reach stability when are surrounded by eight electrons in their valence shell when they combine to form a chemical compound.

From the options, the only compound in which the central atom does not meet the octet rules is BH₃. The central atom is boron (B), which has 3 electrons in its valence shell. When B is combined with hydrogen (H), 3 electrons from the 3 atoms of H are added. The total amount of electrons is 6, fewer than 8 electrons needed to meet the rule.

The compound which is showing exception to the octet rules is BH₃.

According to the octet rule in the outermost valence shell of any compound, eight electrons should present.

Among the given compounds only BH₃ will not satisfy the octet rule, as in the outermost shell of boron atom 3 electron are present following the electronic configuration 1s²,2s²2p¹ because its atomic number is 5. Now this boron atom will form bond with 3 hydrogen atoms and these hydrogen atoms will share 3 electrons to boron atom.

So, total electrons in the outer most shell of BH₃ compound is 3+3=6.

Hence, BH₃ is an exception of octet rule.

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The given question is incomplete. The complete question is:

Butane [tex](C_4H_{10}(g)[/tex], Hf = –125.6 kJ/mol) reacts with oxygen to produce carbon dioxide ([tex]CO_2[/tex] , Hf = –393.5 kJ/mol ) and water [tex](H_2O[/tex], Hf = –241.82 kJ/mol) according to the equation below. What is the enthalpy of combustion (per mole) of [tex]C_4H_{10} (g)[/tex]?

Answer: -2657.5 kJ

Explanation:

The balanced chemical reaction is,

[tex]C_4H_{10}(g)+\frac{13}{2}O_2(g)\rightarrow 4CO_2(g)+5H_2O(g)[/tex]

The expression for enthalpy change is,

[tex]\Delta H=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)][/tex]

[tex]\Delta H=[(n_{CO_2}\times \Delta H_{CO_2})+(n_{H_2O}\times \Delta H_{H_2O})]-[(n_{O_2}\times \Delta H_{O_2})+(n_{C_4H_{10}}\times \Delta H_{C_4H_{10})][/tex]

where,

n = number of moles

[tex]\Delta H_{O_2}=0[/tex] (as heat of formation of substances in their standard state is zero

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

[tex]\Delta H=[(4\times -393.5)+(5\times -241.82)]-[(\frac{13}{2}\times 0)+(1\times -125.6)][/tex]

[tex]Delta H=-2657.5kJ[/tex]

Therefore, the enthalpy of combustion per mole of butane is -2657.5 kJ

Answer:

a. Cs, Rb, Na

Explanation:

Electronegativity is the ability of an element to lose or gain electrons. It is expressed as a number that measures the relative tendency with which atoms of the element attract valence electrons in a chemical bond.

Answer:

A, Iodine

Explanation:

It exists, sodiumiodine.

Answer:

See the answer below

Explanation:

If the root of a plant grows away from the pull of earth's gravity, it will not produce any effect on the plant provided that other conditions of growth are kept normal.

According to research, the force of the Earth's gravity has no effect on the growth features of plants. Plants that were grown away from the influence of gravity still grew normally in a research conducted in space by NASA in 2010.

This thus means that the upward growth of the stem and the downward growth of the root in a negative and positive response to gravity respectively  is dictated by the inherent attributes of plants themselves, and not by the force of the earth's gravity.

Answer:

[tex]\boxed {\boxed {\sf 53, 346 \ Joules}}[/tex]

Explanation:

We are given the specific heat and change in temperature, so we should use this heat formula:

[tex]q=m C \Delta T[/tex]

where m is the mass, C is the specific heat capacity, and ΔT is the change in temperature.

We know the mass is 150 grams. The specific heat of water is 4.184 J/g °C.

Let's find the change in temperature.

Subtract the initial temperature from the final temperature.

Now we know all the values:

[tex]m= 150 \ g \\C= 4.184 J/ g \ \textdegree C \\\Delta T= 85.0 \textdegree C[/tex]

Substitute them into the formula.

[tex]q=(150 \ g) (4.184 \ J/g \ \textdegree C)(85.0 \textdegree C )[/tex]

Multiply all three numbers together. Note that the grams (g) and degrees Celsius (°C) will cancel out. Joules (J) will be the only remaining unit.

[tex]q=(627.6 \ J/ \textdegree C) ( 85.0 \textdegree C)[/tex]

[tex]q=53346 \ J[/tex]

53,346 Joules of heat are required.

The distance from object’s top to its bottom is Height

The distance from object’s side to side is Length

Answer:

b. Gas particles are far apart so they are easy to compress together.

Explanation:

Answer:

Mass = 141.6 g

Explanation:

Given data:

Mass of Kr in gram =  ?

Volume in L = 9.59 L

Temperature = 46.0°C

Pressure = 4.62 atm

Solution:

The given problem will be solve by using general gas equation,

PV = nRT

P= Pressure

V = volume

n = number of moles

R = general gas constant = 0.0821 atm.L/ mol.K  

T = temperature in kelvin

Now we will convert the temperature.

46.0+273 = 319 K

4.62 atm × 9.59 L = n× 0.0821 atm.L/ mol.K  ×319 K

44.3 atm.L = n×26.19 atm.L/ mol

n = 44.3 atm.L / 26.19 atm.L/ mol

n = 1.69 mol

Mass in gram:

Mass = number of moles × molar mass

Mass = 1.69 mol × 83.79 g/mol

Mass = 141.6 g

The question is incomplete, the complete question is; Describe the preparation of 2.00 L of 0.108 M BaCl2 from BaCl2.2H2O

Answer:

See explanation

Explanation:

First we must know the molar mass of the compound = 244.3 g/mol

Now we must calculate the number of moles of BaCl2.2H2O in the solution.

number of moles = concentration * volume = 0.108 M * 2.00 L = 0.216 moles

Now the mass of solid that we need to take can be obtained from;

number of moles = mass/molar mass

mass = number of moles * molar mass

mass = 0.216 moles * 244.3 g/mol

Mass = 52.8 g

Hence, we must weigh 52.8 g of BaCl2.2H2O accurately in a balance and dissolve it in 2 L of water to give 0.108 M solution of BaCl2.2H2O.

Answer:

the answer should be A ! hope this helps :)

Explanation:

Answer:

2.9 g/cm³

Explanation:

From the question given above, the following data were obtained:

Mass = 236.376 g

Volume = 81.5 cm³

Density =?

Density can be defined as the mass of a substance per unit volume of the substance. It can be expressed mathematically as:

Density = mass /volume

With the above formula, we can obtain the density of the object as shown below:

Mass = 236.376 g

Volume = 81.5 cm³

Density =?

Density = mass /volume

Density = 236.376 / 81.5

Density = 2.9 g/cm³

Thus, the density of the object is 2.9 g/cm³

Answer:

The equation is balanced

Explanation:

There are 3Mg,2N,12H,6O and on the other side its the same amount on the other side

Answer:

The answer is B. 11

Explanation:

I did the math and used what I know to find the answer. B is correct.

Answer:

A. When a piece of copper is heated, it combines with oxygen to form copper oxide. The chemical reaction for the same is as follows:

              2 Cu (s) + O2(g) => 2CuO

B. The mass of the piece of copper will remain same and there will be no change in its mass. However, its volume will increase, so its density will decrease.

C. This is so because heating copper in its elemental form is a physical change and there is no change in mass during a physical change. Hence, the mass of copper remain same.

Answer:

Electrostatic

Explanation:

An ionic bond results from the electrostatic attraction between oppositely charged ion.

Usually, metallic ion is positively charge and the non-metallic ion is negatively charged.

The soil is still radioactively contaminated after the Chernobyl nuclear explosion. so NO,  Most of the people who left Chernobyl after the nuclear plant explosion have not  returned. NO, The accident at Chernobyl had not occurred during a safety test.. YES, Temperatures inside the reactor during the explosion were as hot as parts of the Sun's atmosphere. YES, The fuel in the reactor included U-238 from enriched uranium dioxide.

YES, A radioactive cloud blew across Northern Europe after the explosion. NO,Isotopes of the same element have not  the same number of neutrons. but Isotopes are atoms of the same element that have the same number of protons and electrons but different numbers of neutrons YES, When one mole of U-235 undergoes fission, the energy released can power about 400 average U.S. homes for a year.

YES, Nuclear reactors must have control rods to keep a chain reaction from occurring.

YES, Radioactive strontium can lead to bone cancer.

YES, The radioactive iodine released during the explosion still poses a health threat to people in Northern Europe.

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The answer is 1) Plant roots take in water through their roots.

Explanation:The biosphere is made up of all the lifeforms present on the Earth. The hydrosphere is constituted of all the water bodies and sources of water.

When a certain lifeforms from the biosphere reaches out to another sphere, preferably to fetch what if requires to survive, it is said that there is an interaction between two spheres of the larger environment.

These spheres are all interdependent on each other. (i did this before)

Answer:

Plant roots take in water through their roots.

Explanation:

EDGE 2021

Answer:

m = 4450 g

Explanation:

Given data:

Amount of heat added = 4.45 Kcal ( 4.45 kcal ×1000 cal/ 1kcal = 4450 cal)

Initial temperature = 23.0°C

Final temperature = 57.8°C

Specific heat capacity of water = 1 cal/g.°C

Mass of water in gram = ?

Solution:

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = 57.8°C - 23.0°C

ΔT = 34.8°C

4450 cal = m × 1 cal/g.°C × 34.8°C

m = 4450 cal / 1 cal/g

m = 4450 g

Answer:

44.80

Explanation:

Glycogenolysis and Gluconeogenesis occur in the liver due to the action of Cortisol.

It is the process of storing excess glucose for body which can be used at later time. the glycogen stored by the liver is broken down to glucose and dispersed in the body.

Cortisol helps to decrease insulin and increase glucagon. glucagon is type of peptide hormone secreted by pancreatic cells to increase the process of gycogenolysis or gluconeogenis.   it is the primary stress harmone which increases glucose(sugar) in blood.

Gluconeogesis ia that process which tansform non carbohydrate substrate like amino acid ,gycerol into glucose.

Thus, Glycogenolysis and Gluconeogenesis occur in the liver due to the action of Cortisol.

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Answer:

69.09 g

Explanation:

First we calculate the mass of the sample of concentrated H₂SO₄, using the given volume and density:

There are 70.288 grams of solution, of which 98.3% is H₂SO₄. Thus the H₂SO₄ mass is:

Taking into account the definition of density and percentage by mass, the mass of H₂SO₄ in a 38.2 cm³ sample of concentrated sulfuric acid is 69.09 grams.

But first you must know the definition of density. Density is defined as the property that matter, whether solid, liquid or gas, has to compress into a given space.

In other words, density is a quantity that allows us to measure the amount of mass in a certain volume of a substance. Then, the expression for the calculation of density is the quotient between the mass of a body and the volume it occupies:

[tex]density=\frac{mass}{volume}[/tex]

In this case, you know that:

Density= 1.84 [tex]\frac{g}{cm^{3} }[/tex]

Volume= 38.2 cm³

Replacing in the definition of density:

[tex]1.84 \frac{g}{cm^{3} }=\frac{mass}{38.2 cm^{3} }[/tex]

Solving:

mass= 1.84 [tex]\frac{g}{cm^{3} }[/tex]×38.2 cm³

mass= 70.288 g

So, the mass of the solution is 70.288 grams.

The percentage by mass expresses the concentration and indicates the amount of mass of solute present in 100 grams of solution.

In other words, the percentage by mass of a component of the solution is defined as the ratio of the mass of the solute to the mass of the solution, expressed as a percentage.

The percentage by mass is calculated as the mass of the solute divided by the mass of the solution, the result of which is multiplied by 100 to give a percentage. This is:

[tex]percentage by mass=\frac{mass of solute}{mass of solution}x100[/tex]

In this case, you know:

percentage by mass=98.3%

mass of solute= ?

mass of solution= 70.288 grams

Replacing in the definition of percentage by mass:

[tex]98.3=\frac{mass of solute}{70.288 grams}x100[/tex]

Solving:

[tex]\frac{98.3}{100} =\frac{mass of solute}{70.288 grams}[/tex]

[tex]0.983=\frac{mass of solute}{70.288 grams}[/tex]

0.983× 70.288 grams= mass of solute

69.09 grams= mass of solute

The mass of H₂SO₄ in a 38.2 cm³ sample of concentrated sulfuric acid is 69.09 grams.

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density:

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percentage by mass:

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Answer:

B) tetrahedral

Explanation:

From the information:

The given complex is [tex]\Big [Zn (NH_3)_2Cl_2 \Big ]^{2+}[/tex]. In this complex, the number of ligands attached to the central metal atom Zn is 4. This, in turn, affects the coordination number of the complex to be 4. For a coordination number with 4, the likely geometry can either be tetrahedral or square planar, and cis-trans isomerism only occurs in a square planar geometry.

But, from the question, we are informed that the complex does not exhibit cis-trans isomerism, therefore the complex must be tetrahedral.

The molecular formula : C₄H₈O₂

Maybe a compound is 54.5% carbon, 9.1% hydrogen and 36.4% oxygen,so :

mol C :

[tex]\tt \dfrac{54.5}{12}=4.54[/tex]

mol H :

[tex]\tt \dfrac{9.1}{1}=9.1[/tex]

mol O :

[tex]\tt \dfrac{36.4}{16}=2.28[/tex]

Divide by 2.28(the smallest ratio) :

C H : O =

[tex]\tt \dfrac{4.54}{2.28}\div \dfrac{9.1}{2.28}\div \dfrac{2.28}{2.28}=2\div 4\div 1[/tex]

The empirical formula : C₂H₄O

(The empirical formula)n=molecular formula

(2.12+4.1+16)n=88

(44)n=88⇒n=2

Answer:

Indicates the writer's stance on the main idea of a paragraph. The controlling idea appears in the paragraph's topic sentence. ... The final sentence of a paragraph that summarizes the topic sentence using different words. Words and phrases that show how the ideas in sentences and paragraphs are related.

Explanation:

HOPE THIS HELP

PICK ME AS THE BRAINLIEST

Answer:

he last paragraph relates to the main topic because the main topic is about cells and the last paragraph is saying how scientist are still discovering cells but the author says that the new cells are not listed in the article

Explanation:

i had a bad day i hope you have a good one -me    ;

Answer

The Correct Answer Is D

Answer:

Neodymium

Explanation:

The given element is:

          [Xe] 6s² 4f⁴

To solve this problem, we need to find the number of electrons in the element given;

  Xe  has 54 electrons already

  6s² 4f⁴  where:

                 letters are the orbitals

                 6 and 4 are the energy levels

                superscript are the number of electrons

  So,  2 + 4  = 6

 Total number of electrons  = 54 + 6  = 60

The element is Neodymium

[xe] [tex]6s^2[/tex] [tex]4f^4[/tex] is the noble gas configuration for Neodymium. The electron configuration of noble gases follows the general law of electrons filling into atoms' energy levels and orbitals.

The term "noble gas configuration" refers to the periodic table's Group 18 (Group 8A) noble gases' electron configuration. Helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) are some of these gases. The general rule of filling electrons into atoms' energy levels and orbitals applies to the electron configuration of noble gases. Noble gases are extremely stable and inert because their electron shells are totally filled. The electron configuration of atoms that come after noble gases is frequently expressed using the noble gas configuration as a shortcut notation.

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