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3 years ago

11

Which element is this.Its shiny,Is solid at room temperature, has atoms with two valence electrons?A:Lithium B:Strontium C:Alumi

nium D:Silicon

1 answer:

tatyana61 [14]3 years ago

4 0

Answer:

Stronium

Explanation:

It is a metal (and shows classic physical proerties). It also belongs to the second family, meaning it has two valence electrons.

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3 years ago

Define the term pH in acid and base

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a measure of how acidic/base water is.

Explanation:

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1 year ago

what do Mars, Mercury, and Venus have in common? A. They have a gas surface composition and a thick atmosphere. b They have many

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2 years ago

Free-energy change, ΔG∘, is related to cell potential, E∘, by the equationΔG∘=−nFE∘where n is the number of moles of electrons t

mart [117]

Answer:

a) $\Delta G=372490 J$

b) $\Delta G=-568614 J$

Explanation:

a) The reaction:

$Mg(s) +Fe^{2+}(aq) \longrightarrow Mg^{2+}(aq) + Fe(s)$

The free-energy expression:

$\Delta G=-n*F*E$

$E=E_{red}-E_{ox]$

The element wich is reduced is the Fe and the one that oxidates is the Mg:

$-0.44V=E_{red}-(-2.37V)=1.93V$

The electrons transfered (n) in this reaction are 2, so:

$\Delta G=-2mol*96500 C/mol * 1.93 V$

$\Delta G=-372490 J$

b) If you have values of enthalpy and enthropy you can calculate the free-energy by:

$\Delta G=\Delta H - T* \Delta S$

with T in Kelvin

$\Delta G=-675 kJ*\frac{1000J}{kJ} - 298K*-357 J/K$

$\Delta G=-568614 J$

7 0

2 years ago

20 mL of 80°C water is mixed with 20 mL of 0°C water in a perfect calorimeter. What is the final temperature?

dedylja [7]

To calculate for the final temperature, we need to remember that the heat rejected should be equal to the absorbed by the other system. We calculate as follows:

Q1 = Q2
(mCΔT)1 = (mCΔT)2

We can cancel m assuming the two systems are equal in mass. Also, we cancel C since they are the same system. This leaves us,

(ΔT)1 = (ΔT)2
(T - 80) = (0 - T)
T = 40°C

8 0

3 years ago