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Agata [3.3K]
4 years ago
15

Please help me

Chemistry
1 answer:
raketka [301]4 years ago
5 0

Answer: Option C) potassium

Explanation:

According to the reactivity series of metals, potassium K is the most reactive and electropositive metal. it is followed by sodium Na, Magnesium Mg, and Calcium Ca.

Thus, the descending order of reactivity is as follows: K > Na > Mg > Ca which makes potassium displaces the less reactive elements from their respective solutions during chemical reactions.

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Using stoichiometry, determine the mass of powdered drink mix needed to make a 1.0 M solution of 100 mL from C12H22O11
fgiga [73]

Answer:

34.23 g.

Explanation:

<em>Molarity is defined as the no. of moles of a solute per 1.0 L of the solution.</em>

M = (no. of moles of solute)/(V of the solution (L)).

∴ M = (mass/molar mass)of C₁₂H₂₂O₁₁/(V of the solution (L)).

<em>∴ mass of C₁₂H₂₂O₁₁ = (M)(molar mass)(V of the solution (L)</em> = (1.0 M)((342.3 g/mol)/(0.10 L) = <em>34.23 g.</em>

5 0
4 years ago
Refrigerant-134a enters the coils of the evaporator of a refrigeration system as a saturated liquid-vapor mixture at a pressure
Firdavs [7]

Answer:

(a) 0.699 kJ/K

(b) -0.671 kJ/K

(c) 0.028 kJ/K

Explanation:

The Refrigerant-134a flows into the evaporator as a saturated liquid-vapor mixture and flows out as a saturated vapor at a saturation pressure of 160 kPa and temperature of -15.64°C (estimated from the Saturated Refrigerant-134a Temperature Table).

(a) The entropy change of the refrigerant (ΔS_{R-134a}) = Q/T_{1}

Q = 180 kJ

T_{1} = -15.64 + 273.15 = 257.51 K

ΔS_{R-134a} = Q/T_{1} = 180/257.51 = 0.699 kJ/K

(b) The entropy change (ΔS_{c}) of the cooled space (ΔS_{c}) = -Q/T_{2}

Q = -180 kJ

T_{2} = -5 + 273.15 = 268.15 K

ΔS_{c} = Q/T_{2} = -180/268.15 = -0.671 kJ/K

(c) The total entropy change for this process (ΔS_{t}) = ΔS_{R-134a} + ΔS_{c} = 0.699 - 0.671 = 0.028 kJ/K

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4 years ago
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krek1111 [17]
1.)1mps
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6 0
3 years ago
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Why sulphur has two melting point values
Fofino [41]

I don't know how well known/accepted this is (it's in my textbook so I'm guessing it's right), but Sulphur has two forms - the alpha and beta forms ,apparently gamma sulphur exists as well.

The alpha form is rhombic, yellow in color and has a MP of 385.8 K. The beta form is colorless and has a MP of 393 K and is formed by melting rhombic sulphur and cooling it till a crust forms on top. Poke a hole and pour out the liquid inside and you get beta sulphur. The transition point is 369K - below it, alpha sulphur is stable and above it, beta sulphur is stable. Both have helped. I had to pull out an old textbook and that's something that I don't usually do.

8 0
3 years ago
An acid and a base react to form salt and water. Which of the following best describes this type of chemical reaction? Redox Neu
I am Lyosha [343]

Answer:

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Explanation:

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In neutralization reaction equal amount of acid and base react to neutralize each other and equal amount of water and salt are formed. When pH does not reach to 7 its means there is less amount of one of reactant which is not fully neutralize.

Neutralization reactions are also used as first aid. For example when someone is dealing with HCl for cleaning purpose of toilet and get touched. It is advised to neutralize it with soap, milk or egg white.

Example:

Hydrochloric acid when react with the sodium hydroxide, a salt sodium chloride and water are formed.

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HCl + NaOH → NaCl + H₂O

Titration:

Neutralization reactions are also used to determine the concentration of solution. Titration is a quantitative technique in which acid or base is gradually added into the solution whose concentration is to be determine until the neutral point is reached.

3 0
4 years ago
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