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# Daneil

• ### Multiple choice help?

Fuel cells are a particular type of electrochemical cell that require a constant source of chemical fuels, or reactants, during operation. One of the most common types of fuel cells is the alkaline fuel cell, which uses hydrogen and oxygen as reactants.

*(Both questions can have more than 1 answer)

What species are formed at the anode of the alkaline fuel cell?

H2

H2O

O2

OH−

H+

e−

What species are formed at the cathode of the alkaline fuel cell?

O2

H2

OH−

e−

H+

H2O

Chemistry5 months ago

• ### Consider a galvanic cell help?

Consider a galvanic cell in which Al3+ is reduced to elemental aluminum and magnesium metal is oxidized to Mg2+ . Write the balanced half-cell reactions that take place at the cathode and at the anode.

half-cell reaction at the cathode:

half-cell reaction at the anode:

Calculate Δ𝐺∘ at 298 K for the reaction

CS2(l)+3O2(g)⟶CO2(g)+2SO2(g)

based on these reactions.

C(s)+O2(g)⟶CO2(g)Δ𝐺∘=−397.28 kJ/mol

S(s)+O2(g)⟶SO2(g)Δ𝐺∘=−300.19 kJ/mol

C(s)+2S(s)⟶CS2(l)Δ𝐺∘=+62.37 kJ/mol

Δ𝐺∘=

kJ/mol

Chemistry5 months ago
• ### help with chem please?

Calculate the standard entropy, Δ𝑆∘rxn, of the reaction at 25.0 ∘C using the table of thermodynamic properties.

C2H4(g)+H2O(l)⟶C2H5OH(l)

Δ𝑆∘rxn=

J⋅K−1⋅mol−1

Calculate the standard Gibbs free energy of the reaction, Δ𝐺∘rxn. The standard enthalpy of the reaction, Δ𝐻∘rxn, is −44.2 kJ⋅mol−1.

Δ𝐺∘rxn=

kJ⋅mol−1

Determine in which direction the reaction is spontaneous as written at 25.0 ∘C and standard pressure.

neither

forward

reverse

both

• ### chem help?

A critical reaction in the production of energy to do work or drive chemical reactions in biological systems is the hydrolysis of adenosine triphosphate, ATP, to adenosine diphosphate, ADP, as described by the reaction

1. for which Δ𝐺∘rxn=−30.5 kJ/mol at 37.0 °C and pH 7.0. Calculate the value of Δ𝐺rxn in a biological cell in which [ATP]=5.0 mM, [ADP]=0.80 mM, and [HPO2−4]=5.0 mM.

Δ𝐺rxn=      kJ/mol

2. Is the hydrolysis of ATP spontaneous under these conditions?

yes

no

• ### chemistry help?

The decomposition of a generic diatomic element in its standard state is represented by the equation

12X2(g)⟶X(g)

Assume that the standard molar Gibbs energy of formation of X(g) is 5.78 kJ·mol−1 at 2000. K and −63.70 kJ·mol−1 at 3000. K. Determine the value of the thermodynamic equilibrium constant, 𝐾 , at each temperature.

1. At 2000. K, Δ𝐺f=5.78 kJ·mol−1 . What is 𝐾 at that temperature?

𝐾 at 2000. K=

2. At 3000. K, Δ𝐺f=−63.70 kJ·mol−1 . What is K at that temperature?

𝐾 at 3000. K=

• ### Discus fish help ?

Can someone explain why my discus stay in one corner every night like this ? They stay close together in one corner

Fish6 months ago

A strong base is dissolved in 755mL of 0.400M weak acid (Ka=3.93×10−5)  to make a buffer with a pH of  3.96. Assume that the volume remains constant when the base is added.

HA(aq)+OH-(aq) ⟶H2O(l)+A−(aq)

1. Calculate the  pKa value of the acid, and determine the number of moles of acid initially present.

pKa=

initial amount:       mol HA

2. When the reaction is complete, what is the concentration ratio of conjugate base to acid?

[A−][HA]/[A−][HA]=

3. How many moles of strong base were initially added?

• ### chem help?

A volume of 500.0mL of 0.120M NaOH is added to 565mL of 0.250Mweak acid (Ka=8.10×10−5).  What is the  pH  of the resulting buffer?

HA(aq)+OH−(aq)⟶H2O(l)+A−(aq)

pH=