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2 years ago

A sample of 250 g of water are heated from 40°C to 121°C, calculate the amount of heat energy absorbed.

Chemistry

1 answer:

Marysya12 [62]2 years ago

7 0

Answer:

the anwser isn't in the choices

Explanation:

H=MC(change of temp.)

M=mass of water=250g

C=specific heat of water = 4.186 j/g

change in temperature is 121-40= 81

H= 250x4.186x81=84766.5J

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What is the concentration of an alcl3 solution if 150. ml of the solution contains 550. mg of cl- ion?

valina [46]

The concentration of AlCl3 solution if 150 ml of the solution contains 550 mg of cl- ion is 0.0344 M

calculation

concentration = moles /volume in liters

volume in liters = 150 /1000= 0.15 L

number of moles calculation

write the equation for dissociation of Al2Cl3

that is AlCl3 ⇔ Al^3+ + 3 Cl ^-

find the moles of Cl^- formed

moles =mass/molar mass

mass in grams= 550/ 1000 =0.55 grams

molar mass of Cl^- =35.5 g/mol

moles is therefore= 0.55/35.5 =0.0155 moles

by use of mole ration betweem AlCl3 to Cl^- which is 1:3 the moles of AlCl3 is =0.0155 x 1/3= 5.167 x10^-3 moles

concentration of AlCl3 is therefore= 5.167 x10^-3/ 0.15 =0.0344 M

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2 years ago

To break the oxygen-oxygen bonds in a single O2 molecule, 1 × 10–18 J of energy is required. Which of the following wavelengths

Sonbull [250]

E = hc/(lamda)

The lamda symbol is wavelength, which this site does not have. I can represent it with an "x" instead.

Plancks constant, h = 6.626×10^-32 J·s

Speed of light, c = 3.00×10^8 m/s

The energy must be greater than or equal to 1×10^-18 J

1×10^-18 J ≤ (6.626×10^-32 J·s)*(3.0×10^8 m/s) / x

x ≤ (6.626×10^-32 J·s)*(3.0×10^8 m/s) / (1×10^-18 J)

x ≤ 1.99×10^-7 m or 199 nm

The wavelength of light must be greater than or equal to 199 nm

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2 years ago

Net ionic equation for 2AgF(aq) + k2S = Ag2S (s) + 2KF(aq)

tester [92]

Answer:

The net ionic equation shows the actual reaction more clearly and closer to reality because it writes soluble ionic compounds as the ions and then cancel the spectator ions not involved in the chemical reaction . The net ionic equation results shows the actual chemical reaction taking place.

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podryga [215]

Answer:
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Explanation:
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The structure of Polyacrylonitrile is as follow,

--(H₂C-CHCN-)n--

Where n shows the number of Acrylonitrile units joined together in the formation of Polyacrylonitrile. This polymerization reaction can take place by different mechanisms including free radical mechanism, acid catalyzed addition or base catalyzed addition reaction.

The polymerization is shown below,

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Explanation:

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