The pKb value for aqueous ammonia at 25


is 4.8.


What is the correct pKa value for the ammonium ion at this temperature? (Kb denotes the base dissociation constant and Ka denotes the acid dissociation constant.)

It is important to record all accidents and breakages that occur in the laboratory to prevent them from happening again.

Laboratory accident is defined as the type of accident that occurs in the laboratory leading to harm.

Example of laboratory accidents include the following:

A record of these type of laboratory accidents would hel prevent it's reoccurrence.

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Answer:

[tex]\fbox {2 moles}[/tex]

Explanation:

Relation between grams of Carbon and moles :

[tex]\fbox {12 g Carbon = 1 mole}[/tex]

Multiply both sides by 2 :

⇒ 1 x 2 moles = 12 x 2 g

⇒ 2 moles = 24 g

The possible action your solution might contain is amongst [tex]Ag^+[/tex], [tex]Pb^{2+}[/tex], or [tex]Ca^{2+}[/tex].

A solution is a homogeneous mixture of one or more solutes dissolved in a solvent.

NaCl: 20 drops of NaCl were used and no precipitate was formed.

No precipitation formed means the [tex]Cl^-[/tex] cation is soluble in water. From your chart, you might see the halide of [tex]Ag^+[/tex] and [tex]Pb^{2+}[/tex] is insoluble in water, which means they should have formed precipitation but you didn't. This means there's less possibility it contains [tex]Ag^+[/tex] or [tex]Pb^{2+}[/tex], so we are left with only [tex]Ca^{2+}[/tex]. Let's confirm it with the rest.

[tex]Na_2SO_4[/tex] : 20 drops of [tex]Na_2SO_4[/tex] were used yellow precipitate was produced.

Even though all other sulfates form precipitation ( Insoluble in water)

[tex]Na_2CO_3[/tex] : 20 drops of sodium carbonate were used and the silver-blue precipitate was produced.

It seems all of their Carbonate is insoluble in nature. ( which is our case too ).

From the above result, only the reaction with NaCl was deemed to be decisive and it indeed contains [tex]Ca^{2+}[/tex] ions. Means you are correct.

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This is because fall has more weather patterns which are repetitive than summer.

This is defined as the atmospheric condition of a particular place at a given period of time.

The repetitive weather patterns have various effects on the stars which is why they were studied.

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To convert Scientific Notation to a decimal number, Prescribed steps are to be taken given below.

Scientific notation is a way of writing very large or very small numbers.

A number is written in scientific notation when a number between 1 and 10 is multiplied by a power of 10.

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Answer:

Solution Density of aluminium = 2.7 g/Cm 3 In kg/ m 3 = 27 × 1000 10 =2700 kg/ m 3

Explanation:

Not much of one

Answer:

= 64584.7176 g

or

= 64.5847 kg

Explanation:

From our question, we have been asked to find the mass of SO₂ containing 6.075 × 10^26 S atoms.

We know that from Avogadro's constant,

1 mole of a substance contains 6.02 x 10²³ ions/atoms/units

Thus,

1 mole => 6.02 x 10²³ atoms

x moles=> 6.075 × 10²⁶ atoms

We cross multiply;

x moles = (6.075 × 10²⁶ x 1)/(6.02 x 10²³)

= 1009.1362 moles

1 mole of SO2 = 64 g

1009.1362 moles = ?

=>

[tex] \frac{1009.1362 \times 64}{1} [/tex]

= 64584.7176 g

= 64.5847 kg

The specific heat of the metal object with a mass of 22.7g heated to to temperature of 97.0°C and then transferred to an insulated container containing 84.7 g of water at 20.5 ∘C is 0.815J/g°C

How to calculate specific heat?

The specific heat capacity of a metal can be calculated using the calorimetry equation as follows:

Q = mc∆T

Where;

Q = quantity of heat absorbed

m = mass of substance

c = specific heat capacity

∆T = change in temperature

mc∆T (water) = -mc∆T (metal)

84.7 × 4.18 × 3.8 = - (22.7 × c × -72.7)

1345.375 = 1650.29c

c = 0.815J/g°C

Therefore, the specific heat of the metal object with a mass of 22.7g heated to to temperature of 97.0°C and then transferred to an insulated container containing 84.7 g of water at 20.5 ∘C is 0.815J/g°C.

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Answer:

Explanation:

Mining:

    Mining is when certain substances are removed from the Earth, usually in large quantities. Mining can occur below the surface of the Earth via tunnels and caves. It can also occur at surface level through methods such as strip mining, which removes huge amounts of soil in the process

11.48-gram of [tex]KCl0_3[/tex] are needed to produce 6.75 Liters of [tex]O_2[/tex]  gas measured at 1.3 atm pressure and 298 K

The ideal gas law (PV = nRT) relates the macroscopic properties of ideal gases. An ideal gas is a gas in which the particles (a) do not attract or repel one another and (b) take up no space (have no volume).

First, calculate the moles of the gas using the gas law,

PV=nRT, where n is the moles and R is the gas constant. Then divide the given mass by the number of moles to get molar mass.

Given data:

P= 1.3 atm

V= 6.75 Liters

n=?

R= [tex]0.082057338 \;L \;atm \;K^{-1}mol^{-1}[/tex]

T=298 K

Putting value in the given equation:

[tex]\frac{PV}{RT}=n[/tex]

[tex]n= \frac{1.3 \;atm\; X \;6.75 \;L}{0.082057338 \;L \;atm \;K^{-1}mol^{-1} X 298}[/tex]

Moles = 0.3588 moles

Now,

[tex]Moles = \frac{mass}{molar \;mass}[/tex]

[tex]0.3588 moles = \frac{mass}{32}[/tex]

Mass= 11.48 gram

Hence, 11.48-gram of [tex]KCl0_3[/tex] are needed to produce 6.75 Liters of [tex]O_2[/tex] gas measured at 1.3 atm pressure and 298 K

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Answer:

Cu(NO₃)₂ (aq) + 2 KI (aq) ---> CuI₂ (s) + 2 KNO₃

Explanation:

When writing the reaction with the symbols, you need to take into account the charges of the ions. If he charges on the ions do not balance out in a molecule, they need to be made up for in the form of subscripts. For example, copper (+2) and iodine (-1) have charges which do not balance. Thus, to make the molecule neutral, you need to have two iodine atoms (CuI₂).

The unbalanced equation:

Cu(NO₃)₂ (aq) + KI (aq) ---> CuI₂ (s) + KNO₃

Reactants: 1 copper, 2 nitrate, 1 potassium, 1 iodine

Products: 1 copper, 1 nitrate, 1 potassium, 2 iodine

The balanced equation:

1 Cu(NO₃)₂ (aq) + 2 KI (aq) ---> 1 CuI₂ (s) + 2 KNO₃

Reactants: 1 copper, 2 nitrate, 2 potassium, 2 iodine

Products: 1 copper, 2 nitrate, 2 potassium, 2 iodine

The percentage of the area under the normal distribution curve would lie above 98.02 on the x-axis is 2.5 % , option C is the answer.

Normal Distribution is a probability distribution which is symmetric about the mean , The frequency is more near the mean and less far from the mean.

It is given in the data that

10,000 more observations were collected

the percentage of the observations would be greater than 98.02 = ?

According to the 68-95-99.7 rule,

It states that approximately

68% of the observations lie within σ of µ

95% of the observations lie within 2σ of µ.

99.7% of the observations lie within 3σ of µ.

The percentage of the observation between various intervals is attached in the image in the answer.

2.1 percent of the population is distributed in the intervals between two and three standard deviations , which is the zone above 2SD and below 3SD.

As 2.1 % is approximate , Therefore from the given option , 2.5%

The percentage of the area under the normal distribution curve would lie above 98.02 on the x-axis is 2.5 % , option C is the answer.

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Answer:

9.487 L

Explanation:

argon  mole wt = 39.948 gm/mole

             14.3 gm  / 39.948 gm/mole   = .357965 moles of argon

Use Ideal Gas Law:

PV = n RT     where   R = .082057  L-atm / K-mol

V =  .357965 * .082057 * 436 / 1.35  = 9.487 L

Hence,  If the concentration of Acetic acid in vinegar is more than 7%, the limiting reactant is baking soda. If the concentration of Acetic acid in vinegar is less than 7%, the limiting reactant is vinegar.

The limiting reactant (or limiting reagent) is the reactant that gets consumed first in a chemical reaction and therefore limits how much product can be formed.

To solve this problem, it is necessary to know the exact concentration of acetic acid in vinegar, because manufacturers produce many types of vinegar the with different concentrations. Most often, concentration of acetic acid in vinegar ranges from 4% to 8%. In this case, it is possible

to calculate the concentration of vinegar making the assumption that 250 ml of vinegar reacts completely with 24 grams of baking soda.

Acetic acid [tex]CH_3CO_2H[/tex]  reacts with baking soda [tex]NaHCO_3[/tex] according to the equation:

[tex]CH_3CO_2H + NaHCO_3[/tex] → [tex]CH_3CO_2Na + CO_2 + H_2O[/tex]

1. Molar mass of [tex]NaHCO_3[/tex] is 23+1+12+16×3 = 84 g/mol

= [tex]\frac{1 mol \;NaHCO_3}{84 g \;NaHCO_3}[/tex]

= [tex]\frac{24 g \;NaHCO_3 X 1 mol \;NaHCO_3}{84 g \;NaHCO_3}[/tex]

=0.29 mol [tex]NaHCO_3[/tex]

2. From the balanced equation we see that 1 mole of [tex]NaHCO_3[/tex] reacts with 1 mole of [tex]CH_3CO_2H[/tex] , then 0.29 moles of [tex]NaHCO_3[/tex] react with 0.29 moles of [tex]CH_3CO_2H[/tex].

3. Mass of 1 mole of [tex]CH_3CO_2H[/tex] is 12+ 1×3+12+16×2=60 g/mol

= [tex]\frac{0.29 mol \;CH_3CO_2H X \;60 g \;CH_3CO_2H }{1 mol \;CH_3CO_2H}[/tex]

[tex]=17.4 g CH_3CO_2H[/tex]

4. In this step density of vinegar is needed.

Making the assumption that concentration of acetic acid is 7%, we can calculate the mass of acetic acid in 250 ml of vinegar:

Mass of vinegar=Volume × density

= 250 ml ×1.0084 g/ml

=252 g

Mass of acetic acid = mass of vinegar × concentration ÷ 100%

= 252 g × 7% ÷ 100%

= 17.6 g.

17.6 g [tex]CH_3CO_2H[/tex] is very close to 17.4 g [tex]CH_3CO_2H[/tex]. It means, that 250 ml of vinegar with a concentration of acetic acid equal to 7% reacts completely with 24 g of baking soda.

Hence,  If the concentration of Acetic acid in vinegar is more than 7%, the limiting reactant is baking soda. If the concentration of Acetic acid in vinegar is less than 7%, the limiting reactant is vinegar.

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The concentration of sodium chloride in the solution is 5.72% (weight/volume percent).

Weight/volume percent concentration (w/v) expresses the amount of solute (in grams) dissolved in a given volume of solution (in milliliters). Specifically, it is defined as the weight of the solute divided by the volume of the solution, multiplied by 100.

To calculate the weight/volume percent concentration, we need to determine the mass of NaCl per volume of the solution.

First, we need to convert the volume of the solution from milliliters (mL) to liters (L):

67.8 mL = 0.0678 L

Next, we calculate the concentration of NaCl in grams per liter (g/L):

Concentration = Mass of solute ÷ Volume of solution

Concentration = 3.88 g ÷ 0.0678 L

Concentration = 57.2 g/L

Finally, we convert the concentration to weight/volume percent by multiplying by 100:

Weight/volume percent = Concentration x 100

Weight/volume percent = 57.2 g/L x 100

Weight/volume percent = 5.72%

Therefore, the concentration of NaCl in the solution is 5.72% (weight/volume percent).

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Answer:

4.43 g Fe

Explanation:

To find the mass of iron, you need to (1) convert grams Al to moles Al (via molar mass), then (2) convert moles Al to moles Fe (via mole-to-mole ratio from reaction coefficients), and then (3) convert moles Fe to grams Fe (via molar mass). It is important to arrange the conversions/ratios in a way that allows for the cancellation of units (the desired unit should be in the numerator). The final answer should have 3 sig figs because the given value (2.14) has 3 sig figs.

Molar Mass (Al): 26.982 g/mol

2 Al(s) + Fe₂O₃ --->  2 Fe(s) + Al₂O₃(s)

Molar Mass (Fe): 55.845 g/mol

 2.14 g Al           1 mole              2 moles Fe           55.845 g
----------------  x  -----------------  x  --------------------  x  ------------------  =  4.43 g Fe
                         26.982 g           2 moles Al             1 mole

Aluminum reacts with ferric oxide to produce iron by the thermite reaction. The mass of the iron metal that will be formed by the chemical reaction is 4.43 g Fe.

Limiting reagent has been described as reactions that are present in lesser amounts than the other reactant in the reaction that determines the amount of formation of the products and are never left in a reaction.

The balanced thermite reaction is given as:

2 Al(s) + Fe₂O₃ → 2 Fe(s) + Al₂O₃(s)

Molar mass of aluminium = 26.982 g/mol

Molar Mass of iron= 55.845 g/mol

Mass of aluminium (Al) = 2.14 grams

Here, according to the reaction 2 moles of Aluminum are needed to produce 2 moles of iron (Fe).

Moles of aluminum is calculated as:

Moles = mass ÷ molar mass

n = 2.14 ÷ 26.982

= 0.079 mol

As aluminum is the limiting reagent, it determines the formation of iron as:

2 mol Al = 2 mol Fe

0.079 mol Al = 0.079 mol Fe

Mass of iron is calculated as:

Mass = moles × molar mass

mass = 0.079 × 55.845 g/mol

= 4.411 grams

Therefore, 4.43 g Fe will be produced from 2.14 gm Al.

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0.342 x [tex]10^(^1^6^)[/tex])  photons are required to emit 1 joule of energy.

A photon is a particle of light defined as a discrete bundle (or quantum) of electromagnetic (or light) energy.

We need to find the number of photons emitted per second.

So we have E = hc ÷ λ

= (6.6 x [tex]10^-(^3^4^)[/tex]x 3 x [tex]10^8[/tex] m/s) ÷ 6.78 x [tex]10^(^-^7^)[/tex]nm

= 2.92 x [tex]10^(^-^1^9^)[/tex]Joules

Now number of photons per second = I / E (I = intensity)

= 1 x [tex]10^(^-^3^)[/tex] joule / sec ÷ 2.92 x [tex]10^(^-^1^9^)[/tex]joule

= 0.342 x[tex]10^(^1^6^)[/tex]

Hence, 0.342 x [tex]10^(^1^6^)[/tex])  photons are required to emit 1 joule of energy.

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For the reactants,

For the products,

Here, arsenic (+5 to +3) and carbon (+3 to +4) are the only oxidation numbers changing.

Note that an increase in oxidation number means electrons are lost. Thus oxidation is occurring, and a decrease in oxidation number means electrons are being gained, and thus reduction is occurring.

Also, the compound that contains the element being oxidized is the reducing agent, and the compound that contains the element being reduced is the oxidizing agent.

So, the answers are:

name of the element oxidized: Carbon

name of the element reduced: Arsenic

formula of the oxidizing agent: [tex]\text{H}_{3}\text{AsO}_{4}[/tex]

formula of the reducing agent: [tex]\text{H}_{2}\text{C}_{2}\text{O}_{4}[/tex]

Answer:

It's a Ionic compound

Explanation:

To tell if CaO (Calcium oxide) is ionic or covalent (also called molecular) we look at the Periodic Table that and see that Ca is a metal and O is a non-metal. When we have a metal and a non-metal the compound is usually considered ionic.

Because we have a metal and non-metal in CaO there will be a difference in electronegativity between the metal and non-metal. This difference results in an electron(s) being transferred from the metal (lower electronegativity) to the non-metal (higher electronegativity). The results in the metal becoming a postitive ion and the non-metal a negative ion. The two opposite charges are attracted and form the ionic bond between atoms in Calcium oxide.

If a snail crawls at a rate of 228.16cm/s, Its speed in miles per hour will 5.10 miles/hour

The rate at which someone or something moves or operates or is able to move or operate.

Snail covers distance in 1 seconds = 228.16 cm

It covers in 60 seconds (1 min) = 228.16 cm x 60 = 6mtrs

It covers in 60 minutes (1 hour) = 228.16 cm x 60 x 60 = 821376 cm

Now, lets convert cm to miles :

As,                    1 cm = 6.21371 x 10⁻⁶ miles

Thus,     821376 cm = 5.10 miles

hence, If a snail crawls at a rate of 228.16cm/s, Its speed in miles per hour will 5.10 miles/hour

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Answer/Explanation:

The boy's muscle energy changes into potential energy due to the height. it then converts into kinetic energy as it goes further upwards into the air.

0.761 mol of [tex]C_7H_{16}[/tex]  would you have if you have 76.36 grams.

A mole is defined as 6.02214076 × [tex]10^{23}[/tex]of some chemical unit, be it atoms, molecules, ions, or others. The mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance.

Given data:

Mass=76.36 grams

[tex]Moles = \frac{mass}{molar \;mass}[/tex]

[tex]Moles = \frac{76.36 grams}{100.21 g/mol}[/tex]

Moles = 0.761

Hence,  0.761 mol of  [tex]C_7H_{16}[/tex] would you have if you have 76.36 grams.

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180.189 g was the mass of the zinc sample with a specific heat of zinc is 0.390 j/g°C.

The specific heat capacity is defined as the quantity of heat (J) absorbed per unit mass (kg) of the material when its temperature increases 1 K (or 1 °C), and its units are J/(kg K) or J/(kg °C).

Using specific heat capacity formula here:

[tex]C_{Zn}[/tex] × [tex]m_{Zn}[/tex]×  Δ[tex]T_{Zn}[/tex] = [tex]C_{H_2O}[/tex]× [tex]m_{H_2O}[/tex] ×  Δ[tex]T_{H_2O}[/tex]

0.390J/g°C × [tex]m_{Zn}[/tex] ×77.4ºC = 4.184J/g°C×  65.0g ×  20.00ºC.

[tex]m_{Zn}[/tex] = 180.189 g

Hence, 180.189 g was the mass of the zinc sample.

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Answer:

Alcohol has considerable toxic effects on the digestive- and cardiovascular systems. Alcoholic beverages are classified as carcinogenic by the International Agency for Research on Cancer and increase the risk of several cancer types.

Explanation:

please mark me brainlist

Alcohol has a fire hazard symbol because it is extremely flammable and can create fires. Too be specific, ethanol alcohol is the flammable substance.

Answer:

C. electricity conductive

Answer: Decide whether they have designed the best possible product.

Answer:

6PbO +O2 --> 2Pb3O4

Explanation:

The question is incomplete I assume it is

PbO + 02 - Pb304