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Drupady [299]
3 years ago
11

Alkaline earth metals do not react with oxygen. true or false

Chemistry
1 answer:
elena-s [515]3 years ago
3 0
False. Alkaline earth metals react with oxygen.
You might be interested in
How does the A Hreaction relate to the A He of molecules involved in a reaction?
igor_vitrenko [27]

Answer:

B. ΔHreaction = ΔH°f reactants- ΔH°f products

Explanation:

<em>Using Hess's law, it is possible to sum ΔH of several related reactions to find ΔH of a particular reaction</em>.

Having in mind Hess's law, ΔH°f is defined as the change in enthalpy during the formation of 1 mole of substance from its constituent elements (That is, pure elements, mono or diatomics, that have a ΔH° = 0).

For example, in ΔH°f of H₂O, the equation is:

H₂(g) + 1/2O₂(g) → H₂O(g)

The constituent elements with ΔH°f = 0 are H₂(g) and O₂(g).

Now, using Hess's law, you can sum the ΔH°f of substance in a reaction as, for example:

NaOH + HCl → H₂O + NaCl. ΔHr

The ΔH°f for each substance in the reaction is:

NaOH: Na + 1/2H₂ + 1/2O₂ → NaOH <em>(1)</em>

HCl: 1/2H₂ + 1/2Cl₂ → HCl <em>(2)</em>

H₂O: H₂ + 1/2O₂ → H₂O <em>(3)</em>

NaCl: Na + 1/2Cl₂ → NaCl <em>(4)</em>

The algebraic sum of (3) + (4) is -(ΔH°f reactants):

H₂ + 1/2O₂ + Na + 1/2Cl₂ → NaCl + H₂O ΔH°f reactants

This reaction - {(1)+(2)} ΔH°f products

NaOH + HCl → H₂O + NaCl.

ΔHr = ΔH°f reactants- ΔH°f products

In the example, we obtain this relationship that can be expanded for all reactions. Thus, right answer is:

<h3>B. ΔHreaction = ΔH°f reactants- ΔH°f products</h3>

8 0
3 years ago
A magnesium ion, Mg2+, is formed from a magnesium atom, Mg.
konstantin123 [22]

Answer:

The correct row is B.

Explanation:

The formation of the magnesium ion, Mg²⁺, comes from the removal of 2 electrons from the valence shell of the magnesium atom.<em> </em>Since the remotion is of electrons, the nucleus of the atom remains the same, so the number of protons and the number of neutrons does not change.<em> </em>

If the number of proton change, then the atom also change, since the identity of an atom is related to the atomic number which is the same to the proton number.          

Now, if the number of neutrons changes, then we would be in the presence of an isotope of the magnesium atom.        

Therefore, the correct row is B.  

I hope it helps you!                            

5 0
3 years ago
A sample of N2O3(g) has a pressure of 0.046 atm . The temperature (in K) is then doubled and the N2O3 undergoes complete decompo
iogann1982 [59]

Answer:

0.184 atm

Explanation:

The ideal gas equation is:

PV = nRT

Where<em> P</em> is the pressure, <em>V</em> is the volume, <em>n</em> is the number of moles, <em>R</em> the constant of the gases, and <em>T</em> the temperature.

So, the sample of N₂O₃ will only have its temperature doubled, with the same volume and the same number of moles. Temperature and pressure are directly related, so if one increases the other also increases, then the pressure must double to 0.092 atm.

The decomposition occurs:

N₂O₃(g) ⇄ NO₂(g) + NO(g)

So, 1 mol of N₂O₃ will produce 2 moles of the products (1 of each), the <em>n </em>will double. The volume and the temperature are now constants, and the pressure is directly proportional to the number of moles, so the pressure will double to 0.184 atm.

5 0
3 years ago
How much heat is needed to change the temperature of 5g of water from 20 oC to 37 oC?
Dafna1 [17]

Answer:

The answer to your question is Q = 355.64 J

Explanation:

Data

Heat = Q = ?

Temperature 1 = T1 = 20°C

Temperature 2 = T2 = 37°C

mass = m = 5 g

Specific heat = Cp = 4.184 J/g°C

Formula

Q = mCp(T2 - T1)

-Substitution

Q = (5)(4.184)(37 - 20)

-Simplification

Q = (5)(4.184)(17)

-Result

Q = 355.64 J

5 0
3 years ago
Read 2 more answers
The rate law for the decomposition of phosphine () is It takes 135. s for 1.00 M to decrease to 0.250 M. How much time is requir
vova2212 [387]

Answer:

189.71 secs

Explanation:

We know that decomposition is a first order reaction;

So;

ln[A] = ln[A]o - kt

But;

[A]o = 1.00 M

[A] = 0.250 M

t =135 s

Hence;

ln[A] -  ln[A]o = kt

k = ln[A] -  ln[A]o/t

k = ln(1) - ln(0.250)/135

k =0 - (-1.386)/135

k = 1.386/135

k= 0.01

So time taken now will be;

ln[A] -  ln[A]o = kt

t = ln[A] -  ln[A]o/k

t = ln (3) - ln(0.450)/0.01

t = 1.0986 - (-0.7985)/0.01

t = 1.0986 + 0.7985/0.01

t = 189.71 secs

8 0
2 years ago
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