Give the symbol for an element that is:__________

a. a halogen: _______________
b. an alkali metal: _______________
c. a noble gas: _______________
d. an alkaline earth metal : ____________

Answer:

6 mins

Explanation:

The time taken for Ar to effuse can be obtained as follow:

Time for Br₂ (t₁) = 12 mins

Molar mass of Br₂ (M₁) = 2 × 80 = 160 g/mol

Molar mass of Ar (M₂) = 40 g/mol

Time for Ar (t₂) =?

t₂/t₁= √(M₂/M₁)

t₂ / 12 = √(40/160)

Cross multiply

t₂ = 12 × √(40/160)

t₂ = 12 × 0.5

t₂ = 6 mins

Therefore, it will take 6 mins for the same amount of Ar to effused out.

Answer:

10.10

Explanation:

Step 1: Write the basic dissociation reaction for pyridine

C₅H₅N(aq) + H₂O(l) ⇌ C₅H₅NH⁺(aq) + OH⁻(aq)      Kb = 1.9 × 10⁻⁹

Step 2: Calculate [OH⁻]

For a weak base, we will use the following expression.

[OH⁻] = √(Cb × Kb) = √(9.2 × 1.9 × 10⁻⁹) = 1.3 × 10⁻⁴ M

Step 3: Calculate pOH

We will use the definition of pOH.

pOH = -log [OH⁻] = -log 1.3 × 10⁻⁴ = 3.9

Step 4: Calculate pH

We will use the following expression.

pH = 14 - pOH = 14 - 3.9 = 10.10

Answer:

Human life has become very simple by using organic chemicals. The importance of organic chemicals in the daily life and industrial area can be explained as follows. (i) Food Vitamins, proteins, sugar, flour, fats etc. ... (ii) Agriculture is an important place for organic chemical for the growth of agricultural production.

Answer:

somebody small boy is not w e a r d

z0 0m = 257 473 5835 p c:- 12 34

Answer:

C2H3O3

Explanation:

Empirical formula is the simplest whole number ratio of moles of atoms that you can find in a molecule.

In combustion analysis all Carbon reacts producing CO2 and all hydrogen reacts producing H2O. With the differences in masses we can find the mass of oxygen and their moles:

Moles CO2 = Moles C:

14.08g * (1mol/44.01g) = 0.3199 moles C * (12.01g/mol) = 3.8423g C

Moles H2O:

4.32g H2O * (1mol/18.01g) = 0.2399 moles H2O * (2mol H / 1molH2O) = 0.4797moles H = 0.4797g H

Mass O:

12.01g = Mass O + 3.8423g C + 0.4797g H

Mass O = 7.688g O

Moles O:

7.688g O * (1mol/16g) = 0.48 moles O

The ratio of atoms (Dividing in the moles of C that are the lower number of moles):

O: 0.48moles O / 0.3199 moles C = 1.50

C: 0.3199 moles C / 0.3199 moles C = 1

H: 0.4797 moles H / 0.3199 moles C = 1.50

As empirical formula requires whole numbers:

O: 1.50* 2 = 3

C: 1*2 = 2

H: 1.50*2 = 3

The empirical formula is:

Answer:

See explanation

Explanation:

It is possible to generate electricity through a chemical reaction in two ways;

I) use of a voltaic cell where spontaneous chemical processes produce electrical energy.

ii) use of an electrolytic cell where non spontaneous chemical processes produce electrical energy.

The chemical formula of ethane is C2H6

The balanced chemical equation for the combustion of ethane is as follows;

C2H6 + 7/2 O2 ------> 2CO2 + 3H2O

Answer:

5.38 L

Option D.

Explanation:

2 NaOH(s) + 2 Al(s) + 6 H₂O(l)   →  2 NaAl(OH)₄(s)  + 3 H₂(g)

We convert mass of Al to moles:

4.32 g . 1 mol /26.98g = 0.160 moles

As NaOH is in excess, aluminum is the limiting reactant.

We see stoichiometry, were ratio is 2:3.

2 moles of Al can produce 3 moles of hydrogen

Our 0.160 moles may  produce (0.160 . 3)/2 = 0.240 moles of H₂.

We know that 1 mol of any gas at STP conditions is contained in 22.4L

So let's make the conversion factor:

0.240 mol . 22.4L / 1mol = 5.38 L

Answer:

The Density Of Ar (g) At -11°C And 675 MmHg (R =0.08206 L·atm/mol·K, 1 Atm = 760mmHg).

Answer: There are 0.779 moles of gas were added to the bottle.

Explanation:

Given: [tex]n_{1}[/tex] = 0.650 mol,     [tex]P_{1}[/tex] = 730 mm Hg (1 mm Hg = 0.00131579 atm) = 0.96 atm

[tex]n_{2}[/tex] = ?,           [tex]P_{2}[/tex] = 1.15 atm

Formula used is as follows.

[tex]\frac{P_{1}}{n_{1}} = \frac{P_{2}}{n_{2}}[/tex]

Substitute the values into above formula as follows.

[tex]\frac{P_{1}}{n_{1}} = \frac{P_{2}}{n_{2}}\\\frac{0.96 atm}{0.650 mol} = \frac{1.15 atm}{n_{2}}\\n_{2} = 0.779 mol[/tex]

Thus, we can conclude that there are 0.779 moles of gas were added to the bottle.

Answer:

I think

(d) All compounds contain the same elements in the same properties

Answer:

The hot water dissolves the flavor and color components.

Explanation:

Caffeine can be extracted from the tea leaves into hot water because the hot water dissolves the flavor and color components away from the solid vegetable. This is an example of a solid-liquid extraction. We can extracted the aqueous solution and isolated the crude caffeine by converting the components of caffeine into their calcium salts which are insoluble in water. Then the caffeine can be extracted from the water by using methylene chloride.

Answer:

Close to the calculated endpoint of a titration - Partially open

At the beginning of a titration - Completely open

Filling the buret with titrant - Completely closed

Conditioning the buret with the titrant - Completely closed

Explanation:

'Titration' is depicted as the process under which the concentration of some substances in a solution is determined by adding measured amounts of some other substance until a rection is displayed to be complete.

As per the question, the stopcock would remain completely open when the process of titration starts. After the buret is successfully placed, the titrant is carefully put through the buret in the stopcock which is entirely closed. Thereafter, when the titrant and the buret are conditioned, the stopcock must remain closed for correct results. Then, when the process is near the estimated end-point and the solution begins to turn its color, the stopcock would be slightly open before the reading of the endpoint for adding the drops of titrant for final observation.

Explanation:

here is the answer. Feel free to ask for more chem help

Answer:

general formula RCOX, where R represents an alkyl or aryl organic radical group, CO ... represents a halogen atom such as chlorine ... loss of a hydroxyl group (-OH), viz, acetyl,. CH, CO- ..

Answer:

[HI] = 0.704mol

[H2] = 0.048mol

[I2] = 0.148mol

Explanation:

Based on the equilibrium:

H2(g)+I2(g) --> 2HI(g)

The equilibrium constant, K, is defined as:

K = 70 = [HI]² / [H2] [I2]

Where [] could be taken as the moles in equilibrium of each reactant

To know the direction of the equilibrium we need to find Q with the initial moles of each species:

Q = [0.200mol]² / [0.300mol] [0.400mol]

Q = 0.333

As Q < K, the reaction will shift to the right producing more HI. The equilibrium moles are:

[HI] = 0.200mol + 2X

[H2] = 0.300mol - X

[I2] = 0.400mol - X

Replacing in K:

70 = [0.200 + 2X ]² / [0.300 - X] [0.400 - X]

70 = 0.04 + 0.8 X + 4 X² / 0.12 - 0.7 X + X²

8.4 - 49 X + 70 X² = 0.04 + 0.8 X + 4 X²

8.36 - 49.8X + 66X² = 0

Solving for X:

X = 0.252 moles. Right solution

X = 0.502 moles. False solution. Produce negative moles.

Replacing:

[HI] = 0.200mol + 2*0.252 mol

[H2] = 0.300mol - 0.252 mol

[I2] = 0.400mol - 0.252 mol

[HI] = 0.704mol

[H2] = 0.048mol

[I2] = 0.148mol

Answer:

4.00 is the pH of the mixture

Explanation:

The ethyl amine reacts with HNO3 as follows:

C2H5NH2 + HNO3 → C2H5NH3⁺ + NO3⁻

To solve this question we need to find the moles of ethyl amine and the moles of HNO3:

Moles C2H5NH2:

0.0500L * (0.100mol/L) = 0.00500 moles ethyl amine

Moles HNO3:

0.201L * (0.025mol/L) = 0.005025 moles HNO3

That means HNO3 is in excess. The moles in excess are:

0.005025 moles HNO3 - 0.00500 moles ethyl amine =

2.5x10⁻⁵ moles HNO₃

In 50 + 201mL = 251mL = 0.251L:

2.5x10⁻⁵ moles HNO₃ / 0.251L = 9.96x10⁻⁵M = [H+]

As pH = -log [H+]

pH = -log 9.96x10⁻⁵M

pH = 4.00 is the pH of the mixture

Answer:

[tex]M_{a}[/tex] = 0.104 m

Explanation:

This expression is used to determine either the mass or volume of an acid or a base used during titration process.

So that;

[tex]M_{a}[/tex][tex]V_{a}[/tex] = [tex]M_{b}[/tex][tex]V_{b}[/tex]

[tex]M_{a}[/tex] is the mass of the acid

[tex]V_{a}[/tex] is the volume of the acid

[tex]M_{b}[/tex] is the mass of the base

[tex]V_{b}[/tex] is the volume of the base

Given that:

[tex]M_{a}[/tex] x 5.0 m l = 5.2 ml x 0.10 m

[tex]M_{a}[/tex] x 5.0 = 0.52 m

[tex]M_{a}[/tex] = [tex]\frac{0.52}{5.0}[/tex]

      = 0.104

[tex]M_{a}[/tex] = 0.104 m

The mass of the acid used is 0.104 m.

Answer:

It is endothermic because the energy required to break bonds in the reactants is less than the energy released when the products are formed

Explanation:

A reaction may be endothermic or exothermic. In an endothermic reaction, energy is absorbed by the process while in an exothermic process energy is given out by the process.

Recall that the enthalpy change of a reaction = enthalpy of products - enthalpy of reactants

Hence, where the energy required to break bonds in the reactants is less than the energy released when the products are formed, the reaction is endothermic.

For an endothermic reaction, the enthalpy change of the reaction is positive.

In this case, enthalpy of reaction = 920 - (-750) = 1670 kJ/mol

Answer:

The unbalanced chemical equation is

K

2

Cr

2

O

7

+HCl→KCl+CrCl

3

+H

2

O+Cl

2

Balance all atoms except H and O.

K

2

Cr

2

O

7

+10HCl→2KCl+2CrCl

3

+H

2

O+Cl

2

Assign oxidation numbers.

K

2

+6

Cr

2

O

7

+10H

−1

Cl

→2KCl+2

+3

Cr

Cl

3

+H

2

O+

0

Cl

2

The oxidation number of Cr decreases from +6 to +3. Total decrease in the oxidation number of two Cr atoms is 6. The oxidation number of Cl increases from -1 to 0. Total increase in the oxidation number of 2 Cl atoms is 2.

Balance increase in oxidation number with decrease in oxidation number by using appropriate coefficients.

K

2

Cr

2

O

7

+14HCl→2KCl+2CrCl

3

+H

2

O+3Cl

2

Balance O atoms by adding six water molecules on products side.

K

2

Cr

2

O

7

+14HCl→2KCl+2CrCl

3

+7H

2

O+3Cl

2

H atoms are balanced.

K

2

Cr

2

O

7

+14HCl→2KCl+2CrCl

3

+7H

2

O+3Cl

2

This is balanced chemical equation.

The sum of the coefficients of the products is 2+2+7+3=14

Explanation:

High carbon concentration in the deep ocean means increased absorption of carbon to the atmosphere resulting to even greater and harmful amounts of carbon in the atmosphere. Therefore we need to keep a close eye of the deep ocean in the quest to monitor and pump out excess carbon from this part of marine life.

Answer:

C2H3O2

Explanation:

Empirical formula is defined as the simplest whole-number ratio of atoms present in a molecule. To solve this question we need to convert the percentage of each atom to moles using molar mass. With the moles of each atom we can find the ratio:

Moles C -Molar mass: 12.01g/mol-

40.68g * (1mol/12.01g) = 3.387 moles C

Moles H-Molar mass:1g/mol-:

5.12g * (1mol/1g) = 5.12 moles H

Moles O -Molar mass: 16g/mol-

54.19g * (1mol/16g) = 3.387 moles O

Ratio of atoms (Dividing in moles of C that are the lower number of moles):

C = 3.387 moles C / 3.387moles C = 1

H = 5.12moles H / 3.387moles C = 1.5

O = 3.387moles O / 3.387 moles C = 1

This ratio twice (To have only whole-numbers):

C = 2

H = 3

O = 2

Empirical formula of succinic acid:

Answer:

6.52g = Actual yield (g)

Explanation:

The yield of a reaction is:

Percent yield = Actual yield (g) / Theoretical Yield (g) * 100

As 1 mol of isopentyl alcohol produce 1 mol of isopentyl acetate (Theoretical Yield), the theroretical yield of isopentyl acetate is 65.0mmol = 0.0650mol. To solve this question we need to convert the moles of isopentyl acetate to mass using its molar mass (130.19g/mol).

With the equation of percent yield we can find the mass obtained as follows:

Theoretical yield:

0.0650mol * (130.19g/mol) = 8.46g of isopentyl alcohol

Mass produced:

77 = Actual yield (g) / 8.462g * 100

6.52g = Actual yield (g)

The mass of isopentyl acetate that can be produced is 6.52 g

See attached photo

From the balanced equation,

1 mole of isopentyl alcohol reacted to produce 1 mole of isopentyl acetate.

Therefore,

65 mmole (i.e 0.065 mole) of isopentyl alcohol will also react to produce 0.065 mole of isopentyl acetate.

Actual yield = percent × theoretical

Actual yield = 77% × 0.065

Actual yield = 0.05005 mole

Mass = mole × molar mass

Mass of isopentyl acetate = 0.05005 × 130.19

Mass of isopentyl acetate = 6.52 g

Learn more about stoichiometry:

https://brainly.com/question/14735801

Answer:

qualatatiev is fs-hj_jakakak

The question is incomplete, the complete question is shown in the image attached to this answer

Answer:

1) K

2) F

3) Si

4) Br

Explanation:

If an element has a more negative value of electron affinity, then it has a greater ability to attract an electron.

In each of the following pairs of elements, one element has a more negative electron affinity for certain reasons.

Between K and Ca, the incoming electron in K goes into a 4s orbital which is lower in energy and more stable. For Ca, the electron goes into a 3d orbital which is more unstable.

Between Ne and F, Ne already has a filled outermost shell hence the incoming electron goes into the higher energy 3s level. In F, the electron goes into the 2p level and completes it. Hence F has a more negative electron affinity.

Let us recall that half filled and completely filled orbitals are exceptionally stable. Hence, the electron affinity of Si is more negative than that of P because in P, the electron goes into an exceptionally stable half filled orbital.

Recall that the more the value of Zeff, the more negative the electron affinity hence electron affinity increases across a period; hence, Br has a more negative value of electron affinity than Se.

Answer:

a) Heat energy is absorbed.

Explanation:

What occurs in endothermic reactions?

a) Heat energy is absorbed. YES. This is the definition of an endothermic reaction.

b) Water is produced. NO. Endothermic refers to the heat absorbed and not to the products formed.

c) Oxygen is produced. NO. Endothermic refers to the heat absorbed and not to the products formed.

d) Heat energy is released. NO. This is known as an exothermic reaction.

Answer: 3.4 × 10 -1 equal 33.5 cs. May I have brainiest? pls. (the -1 is to the power of the ten.

Answer:

14

73%

Explanation:

The mean Number of years worked :

. (sum of service years) / employees in the

(8+13+15+3+13+28+4+12+4+26+29+3+10+3+17+13+15+15+23+13+12+1+14+14+17+16+7+27+18+24) /

(417 / 30)

= 13.9 years

= 14 years

The percentage of employees who have worked for atleast 10 years :

Number of employees with service years ≥ 10 years = 22 employees

Total number of employees

Percentage (%) = (22 / 30= * 100% = 0.7333 * 100% = 73.33% = 73%

Answer:

dispersion force

Explanation:

Answer:

indicates the number of subshells