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Ket [755]
3 years ago
11

Which of the following is compound?

Chemistry
2 answers:
n200080 [17]3 years ago
7 0
B. NaCl

Explanation: NaCl is made up of sodium and chloride (two different elements makes up a compound)
asambeis [7]3 years ago
4 0

Answer:

fire

Explanation:

Fire is made up of many different substances, so it is not an element. ... Flames are the result of a chemical reaction, primarily between oxygen in the air and a fuel, such as wood or propane. In addition to other products, the reaction produces carbon dioxide, steam, light, and heat

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Cho hai điện tích q1 = 2.10-6 C, q2 = 4. 10-6C, đặt tại A và B trong không khí biết AB = 2 cm. Xác định vectơ cường độ điện trườ
Nitella [24]

Answer:

<h3>A</h3>

Explanation:

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6 0
2 years ago
The average speeds of gas molecules in cylinders A, B, C, and D are 0.01 m/s, 0.005 m/s, 0.1 m/s, and 0.5 m/s, respectively. Whi
Alik [6]
<span>We can relate the average speed of the gas molecules by its kinetic energy. The kinetic energy is the work done by the object due to its motion. It is represented by the formula of the half the velocity squared multiply by the mass of the object. The absolute zero theory is the assumption that at 0 Kelvin or -273.15 degrees Celsius, the gas molecules stop moving. It is because the temperature is severely cold enough to allow movement of the gas molecules. The gas molecule that is closest to the absolute zero is in cylinder B because it moves so slow and its movement is almost near to the absolute zero theory.</span>
4 0
3 years ago
A 25.0 ml sample of a 0.2900 m solution of aqueous trimethylamine is titrated with a 0.3625 m solution of hcl. calculate the ph
Flauer [41]
a) After adding 10 mL of HCl

first, we need to get moles of (CH3)3N = molarity * volume

                                                                 = 0.29 m * 0.025 L
                                                                 = 0.00725M moles
then, we need to get moles of HCl = molarity * volume

                                                          = 0.3625 m * 0.01L
                                                          = 0.003625 moles

so moles of (CH3)3N remaining    = moles of (CH3)3N - moles of HCl
                                                         = 0.00725 - 0.003625

                                                      = 0.003625 moles

and when the total volume = 0.01 L + 0.025L = 0.035 L

∴ [(CH3)3N] = moles remaining / total volume

                    = 0.003625 moles / 0.035L
                    = 0.104 M

when we have Pkb so we can get Kb :

pKb = - ㏒Kb
4.19 = -㏒Kb

∴Kb = 6.5 x 10^-5

when Kb = [(CH3)3NH+] [OH-] / [(CH3)3N]

and by using ICE table we assume we have:

[(CH3)3NH+] = X & [OH] = X 

and [(CH3)3N] = 0.104 -X

by substitution:

∴ 6.5 x 10^-5 = X^2 / (0.104-X)  by solving for X

∴X = 0.00257 M
∴[OH-] = X = 0.00257 M

∴POH = -㏒[OH]

           = -㏒0.00257
           = 2.5

∴ PH = 14 - POH
         = 14 - 2.5
         = 11.5
b) after adding 20ML of HCL:

moles of HCl = molarity * volume
                       = 0.3625 m * 0.02 L

                       = 0.00725 moles

  

the complete neutralizes of (CH3)3N we make 0.003625 moles of (CH3)3NH+ So, now we need the Ka value of (CH3)3NH+:

and when the total volume = 0.02L + 0.025 = 0.045L

∴ [ (CH3)3NH+] = moles / total volume

                          = 0.003625 / 0.045L
                          = 0.08 M
 
when Ka = Kw / Kb 

and we have Kb = 6.5 x 10^-5 & we know that Kw = 1 x 10^-14 

so, by substitution:

Ka = (1 x 10^-14) / (6.5 x 10^-5)

    = 1.5 x 10^-10


when Ka expression = [(CH3)3N][H+] / [(CH3)3NH+]

by substitution:

∴ 1.5 x 10^-10 = X^2 / (0.08 - X)  by solving for X

∴X = 3.5 x 10^-6  M

∴ [H+]= X = 3.5 x 10^-6 M

∴PH = -㏒[H+]

        = -㏒(3.5 x 10^-6)

       = 5.5


C) after adding 30ML of HCl:

moles of HCl = molarity * volume 

                       = 0.3625m * 0.03L

                       = 0.011 moles

and when moles of (CH3)3N neutralized = 0.003625 moles 

∴ moles of HCl remaining    = moles HCl - moles (CH3)3N neutralized

                                                = 0.011moles - 0.003625moles

                                                = 0.007375 moles
when total volume = 0.025L + 0.03L

                                = 0.055L

∴[H+] = moles / total volume

           = 0.007375 mol / 0.055L

            = 0.134 M

∴PH = -㏒[H+]

        = -㏒ 0.134

        = 0.87
8 0
3 years ago
A. Phenol (C6H5OH) is an aromatic compound and a colourless liquid widely used in household products
Olin [163]

Because there are 2 Cl on the left, we will put a coefficient 2in front of HCl on the right side to balance out the Cl. This would result in an unequal amount of H, with 6 on the right side and 7 in the left, so we have to put a coefficient of 2 in front of C6H5OH and C6H4OH on both sides to balance out the H. By doing this, we would obtain an equal amount of H on both sides. The Carbon is already balanced, and so is the Oxygen.

8 0
3 years ago
Briefly describe the following food chain. In your description, explain what would happen if any one of the organisms were to be
poizon [28]
The plants are the primary source of food in a food chain or a food web. The animals which feed on plants will be termed as herbivores or primary consumers like the grasshopper. The organisms feeding on primary consumers will be the secondary consumers like mice. The snake is considered to be a tertiary consumer.

If any one of the organisms were to be removed let’s say the plant, all the other consumers would most likely die since their food supply is no longer available for them to eat. The population of other consumers could fall but could also stay somewhat the same if they eat any other food.


3 0
3 years ago
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