To prepare a sample in a capillary tube for a melting point determination, gently tap the tube into the sample with the ___________ end of the tube down. Continue tapping until the sample. _____________ Then, with the __________ end of the tube down, tap the sample down slowly or __________ to move the sample down faster. Finally, make sure that you can see ___________ in the magnifier when placed in the melting point apparatus before turning on the heat.

Answer:

c.

Explanation:

From the given information:

Critical fracture toughness [tex]K_{IC}[/tex] = 150 MPa.[tex]m ^{1/2}[/tex]

yield strength [tex]\sigma[/tex] = 1500 MPa

surface crack size [tex]a_c[/tex] = ???

The formula for the fracture toughness is can be expressed as:

[tex]K_{IC}= \sigma \sqrt{\pi a_c}[/tex]

replacing our values to solve for the surface crack size, we have:

[tex]150= 1500 \sqrt{\pi a_c}[/tex]

[tex]\dfrac{150}{ 1500} = \sqrt{\pi a_c}[/tex]

[tex]\dfrac{0.1}{1.77} = \sqrt{ a_c}[/tex]

[tex]a_c[/tex] = 0.0564²

[tex]a_c[/tex] = 0.0032 m

[tex]a_c[/tex] = 0.32 cm

Answer:

27 g/mol of E

Explanation:

Note that percentage by mass= mass of each element present. So, since there is 90% of E, there is 90g of E present. By implication, there are 10g of H corresponding to 10%H. Note that there is 100g of EH3

1 moles of E corresponds to 90 g of E

Mole ratio of E: H= 1:3

Thus

Number of moles of H = 10g/ 1g/ mol = 10 moles of H

Since E contains 1/3 the number of moles of H

Number of moles of E = 1/3 × 10 = 3.33 moles of E

Molar mass of E= mass of E/ number of moles of E

Since mass of E = 90 g

Molar mass of E = 90g/3.33 moles

Molar mass of E = 27 g/mol

Answer:

481.16 cm³

Explanation:

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

Height (h) = 11.72 cm

Diameter (d) = 7.23 cm

Pi (π) = 3.14159

Volume of cylinder (V) =?

Next, we shall determine the radius. This can be obtained as follow:

Diameter (d) = 7.23 cm

Radius (r) =?

r = d/2

r = 7.23 / 2

r = 3.615 cm

Finally, we shall determine the volume of the cylinder. This can be obtained as shown below:

Height (h) = 11.72 cm

Pi (π) = 3.14159

Radius (r) = 3.615 cm

Volume of cylinder (V) =?

V = πr²h

V = 3.14159 × 3.615² × 11.72

V = 3.14159 × 13.068225 × 11.72

V = 481.16 cm³

Therefore, the volume of the cylinder is 481.16 cm³.

Answer:

The equation which will tell us how much of A that is mis inmthe water layer after partitioning is: 7 = (17 - x) g / 150 mL ÷ x g /100 mL

Explanation:

A partition coefficient is the ratio of the concentration of a substance in one solvent phase to the concentration in a second solvent phase when the two concentrations are at equilibrium. Usually the two phases are an organic phase and an aqueous phase. Thus, the partition coefficient K, of a compound is the ratio of the compound's concentration in the organic layer compared to the aqueous layer.

K = C₁/C₂ at equilibrium

In the compound A given, CH₂Cl₂ is the organic phase while water is the aqueous phase

Amount of A that is partitioned in between dichloromethane, CH₂Cl₂ and water, H₂O is 17.0 g

Let the amount of A that is dissolved in water be x g

Solubility of A in water given in g/mL = (x / 100) g/ml

Amount of A dissolved in dichloromethane, CH₂Cl₂ = (17 - x) g

Solubility of A in dichloromethane, CH₂Cl₂ given in g/mL = (17 - x/150) g/mL

Since the partition coefficient, K of compound A when comparing its solubility in CH₂Cl₂ to water is 7, that is;

K = [solubility of A in g/ml in CH₂Cl₂] / [solubility of A in g/ml in H2O] = 7

The equation for the amount of A in the water layer is given as follows:

7 = (17 - x) g / 150 mL ÷ x g /100 mL

Solving for x

7 = (17 -x) × 100 / 150x

7 × 150x = (17 - x) × 100

1050x = 1700 - 100x

1150x = 1700

x = 1700/1150

x = 1.48 g

Answer:

Magnetic force obeys an inverse square law with distance. ... If the distance between two magnets is doubled the magnetic force between them will fall to a quarter of the initial value. (F/4) If the distance between two magnets is halved the magnetic force between them will increase to four times the initial value.

Answer:

Spontaneous at only low temperature. I made a chart for my AP Chem class if you want to refer to it.

Answer:

Amount of water

The thermometer

Explanation

In an experiment, there is always a dependent variable and an independent variable. The independent variable is manipulated and its effect on the dependent variable is observed.

The control is that factor in the experiment that must remain constant so that effect of the independent variable on the dependent variable can be observed.

In this case, the independent variable is the amount of sodium chloride while the dependent variable is the temperature at which the solution boils.

The controls must be the amount of water which must be held constant and the same thermometer used to measure the temperature so that the effect of the amount of sodium chloride on the temperature of the solution can be studied.

The following are the controls in the experiment:

The beaker with 100 mL of water without any sodium chloride.

The temperature of the Bunsen burner.

The type of thermometer used.

The control(s) in the experiment are the beaker with 100 mL of water without any sodium chloride. This beaker is used to compare the boiling points of the other beakers, which have different amounts of sodium chloride added.

The control beaker ensures that any differences in boiling point are due to the amount of sodium chloride added, and not to other factors, such as the temperature of the Bunsen burner or the type of thermometer used.

The other factors that could affect the boiling point of water, such as the humidity of the air or the altitude, are kept constant in the experiment.

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Answer:

Explanation:

First we convert 52.80 g of NaCl to moles, using its molar mass:

To determine the molality, we convert 150.0 g of water to kg:

As for the molarity, we determine the total mass of solution:

And calculate the volume, using the density:

Finally we calculate the molarity:

The question is incomplete, the complete question is;

Groups of the periodic table correspond to elements with a. the same color b. the same atomic number c. similar chemical properties d. similar numbers of neutrons

Answer:

similar chemical properties

Explanation:

In the periodic classification of elements, elements are divided into groups and periods. Elements in the same group of the periodic table have the same number of outermost electrons and share very similar chemical properties.

Elements in the same period have the same number of shells and the same maximum energy level of the outermost electron. Chemical properties carry markedly across a period.

Answer:

moles CO₂ produced from combustion of 7.9 mole of C₅H₁₂ = 39.5 moles CO₂

Explanation:

              C₅H₁₂      +   8O₂      =>      6H₂O      +      5CO₂

Given:   7.9moles    excess            _____            ? moles

From Equation, 1 mole C₅H₁₂ =============>  5 moles CO₂

Given            7.9 mole C₅H₁₂  =============>         X

Solving for 'X' using ratio and proportion ...

1mole C₅H₁₂ / 7.9mole C₅H₁₂ =  5mole CO₂ / X

=> X = 5 mole CO₂ x  7.9mole C₅H₁₂ / 1mole C₅H₁₂  =  39.5 moles CO₂

≅ 40 moles CO₂ (2 sig. figs.)

Answer:

Platinum is especially good for this because it is unreactive, and does not produce a color in the flame which will mask the presence of other metals.

Hope this answer is right!

Answer:

Hey mate, here is your answer

1. Platinum doesn't impart any color to the flame.

2. It is not oxidised under the high temperature of the flame from a bunsen burner.

3. It is almost chemically inert. Even at high temperatures, it remains unattacked by free radicals / acid radicals.

Therefore, platinum wire is crucial for a flame test. Also, a platinum wire should be thoroughly cleaned before using it for a new flame test.

A platinum wire is cleaned by dipping it into concentrated HNO3 and then placing it in the non luminous part of the bunsen flame. Otherwise, the perviously tested radicals will impart color to the flame, which may cause confusion.

Explanation:

Hope it helps you

Answer:

d,e

Explanation:

The main consequence of exposure to the chemicals at Love Canal was:

allergies.

hair loss.

upper respiratory disease.

Answer:

0.6 ohm

Explanation:

voltage = 1.5 V

current = 2.5 A

resistence = ?

V = IR

1.5 = 2.5 * R

1.5 / 2.5 = r

0.6 = R

therefore resistence is 0.6 ohm

Answer:

HCl  is a acid

Explanation:

NaOH is base

Nacl is salt

Explanation:

74.92 g.

(The mass of one mole of arsenic is 74.92 g.

Answer:

Aldehydes and Ketones

Both aldehydes and ketones contain a carbonyl group, a functional group with a carbon-oxygen double bond. The names for aldehyde and ketone compounds are derived using similar nomenclature rules as for alkanes and alcohols, and include the class-identifying suffixes -al and -one, respectively:



In an aldehyde, the carbonyl group is bonded to at least one hydrogen atom. In a ketone, the carbonyl group is bonded to two carbon atoms:





As text, an aldehyde group is represented as –CHO; a ketone is represented as –C(O)– or –CO–.

In both aldehydes and ketones, the geometry around the carbon atom in the carbonyl group is trigonal planar; the carbon atom exhibits sp2 hybridization. Two of the sp2 orbitals on the carbon atom in the carbonyl group are used to form σ bonds to the other carbon or hydrogen atoms in a molecule. The remaining sp2 hybrid orbital forms a σ bond to the oxygen atom. The unhybridized p orbital on the carbon atom in the carbonyl group overlaps a p orbital on the oxygen atom to form the π bond in the double bond.

Like the C=OC=O bond in carbon dioxide, the C=OC=O bond of a carbonyl group is polar (recall that oxygen is significantly more electronegative than carbon, and the shared electrons are pulled toward the oxygen atom and away from the carbon atom). Many of the reactions of aldehydes and ketones start with the reaction between a Lewis base and the carbon atom at the positive end of the polar C=OC=O bond to yield an unstable intermediate that subsequently undergoes one or more structural rearrangements to form the final product (Figure 1).

Figure 1. The carbonyl group is polar, and the geometry of the bonds around the central carbon is trigonal planar.

The importance of molecular structure in the reactivity of organic compounds is illustrated by the reactions that produce aldehydes and ketones. We can prepare a carbonyl group by oxidation of an alcohol—for organic molecules, oxidation of a carbon atom is said to occur when a carbon-hydrogen bond is replaced by a carbon-oxygen bond. The reverse reaction—replacing a carbon-oxygen bond by a carbon-hydrogen bond—is a reduction of that carbon atom. Recall that oxygen is generally assigned a –2 oxidation number unless it is elemental or attached to a fluorine. Hydrogen is generally assigned an oxidation number of +1 unless it is attached to a metal. Since carbon does not have a specific rule, its oxidation number is determined algebraically by factoring the atoms it is attached to and the overall charge of the molecule or ion. In general, a carbon atom attached to an oxygen atom will have a more positive oxidation number and a carbon atom attached to a hydrogen atom will have a more negative oxidation number. This should fit nicely with your understanding of the polarity of C–O and C–H bonds. The other reagents and possible products of these reactions are beyond the scope of this chapter, so we will focus only on the changes to the carbon atoms:

Answer:

A process that involves rearrangement of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction.

Explanation:

Pretty much just not a physical reaction or otherwise

Answer:

n = 0.21 moles

Explanation:

Given that,

Volume, V = 0.84 L

Pressure, P = 4.6 atm

T = 222 K

We need to find the number of moles of Neon gas. We know that,

PV = nRT

Where

n is the number of moles

R i the gas constant, R = 0.08206 L-atm/mol-K

Put all the values,

[tex]n=\dfrac{PV}{RT}\\\\n=\dfrac{4.6\times 0.84}{0.08206 \times 222}\\\\n=0.21\ \text{moles}[/tex]

So, there are 0.21 moles of Neon gas.

Answer:

Crystalline solids, or crystals, have distinctive internal structures that in turn lead to distinctive flat surfaces, or faces. The faces intersect at angles that are characteristic of the substance. When exposed to x-rays, each structure also produces a distinctive pattern that can be used to identify the material.

Explanation:

Answer:

Match each term with the best description.

a. The electrode where oxidation occurs: Anode

b. A device that produces electricity: Galvanic cell

c. The connection between two half-cells: salt bridge

d. The electrode where reduction occurs: Cathode

e. A device that consumes electricity: Electrolytic cell

f. A device that utilizes redox reactions to either consume or produce electricity: Electrochemical cell.

Explanation:

a.The electrode where oxidation occurs is called the anode.

Oxidation is losing of electrons.

b. Galvanic cell produces electricity by using redox chemical reaction.

It is also called a voltaic cell or electrochemical cell.

c. The connection between two cells is called a salt bridge.

It will not allow the solutions to diffuse with each other.

It maintains electrical neutrality.

d. The electrode where reduction occurs: Cathode

Reduction means the gaining of electrons.

e. Electrolytic cell is the one that consumes electricity and then produces a chemical change.

f. A device that utilizes redox reactions to either consume or produce electricity: Electrochemical cell.

Answer:

The correct answer is - 5L.

Explanation:

From the ideal gas equation -

pv=nRT

p = pressure

v =volume

Here nRT is constant so

P would be inversely proportioned to v

So, p1/p2 = v2/v1

Putting values:

2/4(2) = v2/20 (p2 = 4 times of P1)

2/8 = v2/20

V2 = 5

Thus, the correct volume at new pressure would be - 5 L.

Answer:

Firstly, the molecular formula of water would be H2O. Secondly, it expresses the amount of different atoms in the water molecule. In this case, H2 would be two Hydrogen atoms, and O would be 1 Oxygen atom.

Explanation:

Hope this helped!

Answer:

It basically means that water contains 2 atoms of Hydrogen and 1 atom of Oxygen.

Answer:

No, the correct empirical formula is [tex]C_3H_7[/tex].

Explanation:

Hello there!

In this case, according to the given information, it turns out necessary for us to bear to mind the fact that empirical formulas must not be expressed in decimal numbers, for that reason, we need to multiply the given empirical formula by 2 to get the correct one:

[tex]C_3H_7[/tex]

Which is now possible.

Regards!

Answer:

(E)-1-phenylbut-1-ene

Explanation:

2-phenyl-4 bromobutane is an amphetamine that contains a phenyl group. It forms a major stable product with other reacting agents.

The major organic product that is obtained from the sequence of the reactions of the 2-phenyl-4 bomobutane when it reacts with [tex]NaN_3[/tex] is the (E)-1-phenylbut-1-ene.

Thus the answer is 2-phenyl-4 bromobutane is an amphetamine that contains a phenyl group. It forms a major stable product with other reacting agents.

The major organic product that is (E)-1-phenylbut-1-ene.

Answer:

The amswer would be A due to the ratio between ethane and carbon dioxide being 1:2. Due to this, you double the moles that are reacting

If the salt water is heated, the water turns into steam and the salt remains because the water has a lower boiling point than the salt.

The  following points can be considered:

The process involved when salt water is heated:

Therefore, the answer is water has a lower boiling point than salt.

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Answer:

0.077 mole of ClF₃.

Explanation:

The balanced equation for the reaction is given below:

Cl₂ + 3F₂ —> 2ClF₃

From the balanced equation above,

3 moles of F₂ reacted to produce 2 moles of ClF₃.

Finally, we shall determine the number of mole of ClF₃ produced by the reaction of 0.115 mole of F₂. This can be obtained as follow:

From the balanced equation above,

3 moles of F₂ reacted to produce 2 moles of ClF₃.

Therefore, 0.115 mole of F₂ will react to to produce = (0.115 × 2)/3 = 0.077 mole of ClF₃.

Thus, 0.077 mole of ClF₃ was obtained from the reaction.

Formula is (CH3)2CHCH2C(CH3)3 and the name is 2,2,4-trimethylpentane