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LenaWriter [7]
3 years ago
10

5) answer is A

Chemistry
1 answer:
Burka [1]3 years ago
3 0

Answer:

A)  positive; added

Explanation:

Based on the reaction:

2NaHCO3(s) + 129kJ → Na2CO3(s) + H2(g) + CO2(g)

<em>2 moles of NaHCO3 requires 129kJ to produce 1 mole of Na2CO3, 1 mole of H2 and 1 mole of CO2.</em>

<em />

That means, the energy must be added being, thus, an exothermic reaction. The exothermic reactions have ΔH >0.

Thus, right answer is:

A)  positive; added

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Galvanized nails are iron nails that have been plated with zinc to prevent rusting. The relevant reaction is
fomenos

Answer:

1.18 × 10⁷ c

Iron is the anode and zinc is the cathode.

Explanation:

Let's consider the reduction of Zn²⁺.

Zn²⁺(aq) + 2 e⁻ ⇒ Zn(s)

<em>How many coulombs of charge are needed to produce 61.2 mol of solid zinc?</em>

<em />

We can establish the following relations:

  • When 2 moles of electrons circulate, 1 mol of Zn is produced.
  • 1 mole of electrons have a charge of 96468 c (Faraday's constant).

Then, for 61.2 mol of Zn:

61.2molZn.\frac{2mole^{-} }{1molZn} .\frac{96468c}{1mole^{-}} =1.18 \times 10^{7} c

<em>Identify the anode and cathode when plating an iron nail with zinc.</em>

The anode is where the oxidation takes place and the cathode is where the reduction takes place.

Anode (oxidation): Fe(s) ⇒ Fe²⁺(aq) + 2 e⁻

Cathode (reduction): Zn²⁺(aq) + 2 e⁻ ⇒ Zn(s)

3 0
3 years ago
For the gas phase decomposition of 1-bromopropane, CH3CH2CH2BrCH3CH=CH2 + HBr the rate constant at 622 K is 6.43×10-4 /s and the
Radda [10]

Answer is: activation energy of this reaction is 212,01975 kJ/mol.<span>
Arrhenius equation: ln(k</span>₁/k₂) = Ea/R (1/T₂ - 1/T₁).<span>
k</span>₁ = 0,000643 1/s.<span>
k</span>₂ = 0,00828 1/s.

T₁ = 622 K.

T₂ = 666 K.

R = 8,3145 J/Kmol.

<span> 1/T</span>₁ = 1/622 K = 0,0016 1/K.<span>
1/T</span>₂ = 1/666 K = 0,0015 1/K.<span>
ln(0,000643/0,00828) = Ea/8,3145 J/Kmol · (-0,0001 1/K).
-2,55 = Ea/8,3145 J/Kmol </span>· (-0,0001 1/K).<span>
Ea = 212019,75 J/mol = 212,01975 kJ/mol.</span>

6 0
3 years ago
What shows the substance at the highest temperature?
Tcecarenko [31]

Answer:

needs more information

Explanation:

6 0
3 years ago
Read 2 more answers
Ammonia, NH3 is a common base with Kb of 1.8 X 10-5. For a solution of 0.150 M NH3:
Vesnalui [34]

The concentrations : 0.15 M

pH=11.21

<h3>Further explanation</h3>

The ionization of ammonia in water :

NH₃+H₂O⇒NH₄OH

NH₃+H₂O⇒NH₄⁺ + OH⁻

The concentrations of all species present in the solution = 0.15 M

Kb=1.8 x 10⁻⁵

M=0.15

\tt [OH^-]=\sqrt{Kb.M}\\\\(OH^-]=\sqrt{1.8\times 10^{-5}\times 0.15}\\\\(OH^-]=\sqrt{2.7\times 10^{-6}}=1.64\times 10^{-3}

\tt pOH=-log[OH^-]\\\\pOH=3-log~1.64=2.79\\\\pH=14-2.79=11.21

8 0
3 years ago
A metal ion (X) with a charge of 4+ is attracted to non metal ion (Z) with a charge of 3-. Which of these formulas represents th
pav-90 [236]

Answer:  X_3Z_4

Explanation:

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.

Here metal X is having an oxidation state of +4 called as X^{4+} cation and Z^{3-} is an anion with oxidation state of -3. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral X_3Z_4

X_3Z_4 is the formula of the resulting compound.

6 0
3 years ago
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