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ZanzabumX [31]
3 years ago
5

I need help with 17,18,19,& 21

Chemistry
1 answer:
valentinak56 [21]3 years ago
3 0

Answer:

17. tie hair up

wear goggles

18. i don't know

19. you light it on the side of the box

20. it should be orange because that is the safest.

21. you turn down the electricity thing

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What is the freezing point of an aqueous solution that has 25.00 g of calcium iodide dissolved in 1250 g of water?
ozzi

Answer:

<u></u>

  • <u>- 0.380ºC</u>

Explanation:

The lowering of the freezing point of a solvent is a colligative property ruled by the formula:

  • \Delta T_f=K_f\times m\times i

Where:

  • ΔTf is the lowering of the freezing point
  • Kf is the molal freezing constant of the solvent: 1.86 °C/m
  • m is the molality of the solution
  • i is the van't Hoff factor: the number of particles (ions) per unit of ionic compound.

<u />

<u>a) molality, m</u>

  • m = number of moles of solute/ kg of solvent
  • number of moles of CaI₂ = mass in grams/ molar mass
  • number of moles of CaI₂ = 25.00g / 293.887 g/mol = 0.0850667mol
  • m = 0.0850667mol/1.25 kg = 0.068053m

<u>b) i</u>

  • Each unit of CaI₂, ideally, dissociates into 1 Ca⁺ ion and 2 I⁻ ions. Thus, i = 1 + 2 = 3

<u />

<u>c) Freezing point lowering</u>

  • ΔTf =  1.86 °C/m × 0.068053m × 3 = 0.3797ºC ≈ 0.380ºC

<h2>I have problems to upload the full answer in here, so I attach a pdf file with the whole answer.</h2>
Download pdf
6 0
3 years ago
An atom or ion has 41 neutrons, 36 protons, and 36 electrons. Identify the clement symbol, and determine the mass
Paul [167]

The atom is krypton and its symbol is Kr.

the mass number is 41 + 36 = 77

its charge is 0 as it is a noble gas.

7 0
3 years ago
An example of a physical property of an element is the element's ability to
FromTheMoon [43]

Answer:

dissolve

Explanation:

When it dissolves , no chemicals are formed and it is considered as a physical property.

4 0
3 years ago
Read 2 more answers
List the advantages and disadvantages of restricting antibioticuse
vlada-n [284]

Answer:

Advantages - less chances of developing resistant strains, less cost, less side effects, allowing the body to mount immune response

Disadvantages - inadequate/incomplete cure leading to complications, longer stay in the hospital

Explanation:

3 0
4 years ago
Ammonia NH3 may react with oxygen to form nitrogen gas and water.4NH3 (aq) + 3O2 (g) \rightarrow 2 N2 (g) + 6H2O (l)If 2.15g of
bagirrra123 [75]

Answer:

NH3 is the limiting reactant

The % yield is 36.1 %

Explanation:

<u>Step 1: </u>Data given

Mass of NH3 = 2.15 grams

Mass of O2 = 3.23 grams

Molar mass of NH3 = 17.03 g/mol

Molar mass of O2 = 32 g/mol

volume of N2 produced = 0.550 L

Temperature = 295 K

Pressure = 1.00 atm

<u>Step 2:</u> The balanced equation:

4NH3 (aq) + 3O2 (g) → 2 N2 (g) + 6H2O (l)

<u>Step 3:</u> Calculate moles of NH3

Moles NH3 = Mass NH3 / Molar Mass NH3

Moles NH3 = 2.15 grams / 17.03 g/mol

Moles NH3 = 0.126 moles

<u>Step 4:</u> Calculate moles of O2

Moles O2 = 3.23 grams / 32 g/mol

Moles O2 = 0.101 moles

<u>Step 5: </u>Calculate the limiting reactant

For 4 moles NH3 consumed, we need 3 moles of O2 to produce, 2 moles of N2 and 6 moles of H2O

NH3 is the limiting reactant. It will completely be consumed ( 0.126 moles).

O2 is in excess, there will be 3/4 * 0.126 = 0.0945 moles consumed

There will remain 0.101 - 0.945 = 0.0065 moles of O2

<u>Step 6:</u> Calculate moles of N2

For 4 moles NH3 consumed, we need 3 moles of O2 to produce, 2 moles of N2 and 6 moles of H2O

For 4 moles NH3 , we'll have 2 moles of N2 produced

For 0.126 moles NH3 consumed, we'll have 0.063 moles of N2 produced.

<u>Step 7</u>: Calculate volume of N2 produced

p*V = n*R*T

⇒ with p = the pressure of the gas = 1.00 atm

⇒ with V = the volume = TO BE DETERMINED

⇒ with n = the number of moles N2 = 0.063 moles

⇒ with R = the gasconstant = 0.08206 L*atm/K*mol

⇒ with T = the temperature = 295

V = (nRT)/p

V = (0.063*0.08206*295)/1

V = 1.525 L = theoretical yield

<u>Step 8:</u> Calculate the % yield

% yield = actual yield / theoretical yield

% yield = (0.550 L / 1.525 L)*100%

% yield = 36.1 %

4 0
3 years ago
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