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mojhsa [17]
3 years ago
13

Hydrofluoric acid, hf(aq), cannot be stored in glass bottles because compounds called silicates in the glass are attacked by the

hf(aq). sodium silicate (na2sio3), for example, reacts as shown below. na2sio3(s) + 8 hf(aq) h2sif6(aq) + 2 naf(aq) + 3 h2o(l) (a) how many moles of hf are needed to react with 0.340 mol of na2sio3?
Chemistry
1 answer:
Trava [24]3 years ago
5 0
1) Chemical equation

Na2 SiO3 (s) + 8 HF (aq) ---> H2 Si F6 (aq) + 2 Na F (aq) + 3H2O (l)

It is balanced

2) Molar ratios

1 mol Na2 SiO3 : 8 mol HF.

3) Proportion

0.340 mol Na2 SiO3 * 8 mol HF / 1mol Na2SiO3 = 2.72 mol HF.

Answer: 2.72 mol HF

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Engine size is measured by how much air the cylinders displace. A 1996 Pontiac V8 has an engine size of 316.6 cubic inches. What
inna [77]

The size of this engine in cubic meters is 0.0052 m^{3}.

<u>Explanation:</u>

As it is stated that engine size can be measured depending upon the amount of air the cylinders displace, it is also stated that the engine of model Pontiac V8 has a size of 316.6 cubic inches. The problem is to convert the size of engine in cubic meters. We know that 1 inch = 0.0254 m.

Then 1 inch^{3}=(0.0254)^{3} m^{3}

As here the size of engine is 316.6 cubic inches, then in metres it will be

    316.6 \text { inches }^{3}=316.6 \times(0.0254)^{3} \mathrm{m}^{3}=0.0052 \mathrm{m}^{3}

Thus, the size of the engine in cubic meters will be 0.0052 m^{3}.

3 0
3 years ago
If 50.0 grams of HCl were dissolved in enough water to make a solution with a total volume of 5.0 liters, what would be the mola
SVETLANKA909090 [29]

The molarity of a solution is found to be 10 M.

Explanation:

  • Molarity of a solution = <u>moles solute</u>

                                        Litres solution

  • Therefore,M =<u> 50</u>

                        5

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5 0
3 years ago
Based on the sign of E cell, classify these reactions as spontaneous or non spontaneous as written.? assume standard conditions.
sammy [17]
A electrochemical reaction is said to be spontaneous, if E^{0} cell is positive. 

Answer 1:
Consider reaction: <span>Ni^2+ (aq) + S^2- (aq) ----> + Ni (s) + S (s) 

The cell representation of above reaction is given by;
    </span>S^{2-}/S //  Ni^{2+}/Ni

Hence, E^{0}cell =  E^{0} Ni^{2+/Ni} -  E^{0} S/S^{2-}
we know that, {E^{0} Ni^{2+}/Ni  = -0.25 v
and {E^{0} S/ S^{2-}  = -0.47 v

Therefore, E^{0} cell = - 0.25 - (-0.47) = 0.22 v

Since,  E^{0} cell is positive, hence cell reaction is spontaneous
.....................................................................................................................

Answer 2: 
Consider reaction: <span>Pb^2+ (aq) +H2 (g) ----> Pb (s) +2H^+ (aq)
</span>
The cell representation of above reaction is given by;
    H_{2} /  H^{+} //  Pb^{2+} /Pb

Hence, E^{0}cell = E^{0} Pb/Pb^{2+} - E^{0} H_{2}/H^{+}
we know that, {E^{0} Pb^{2+}/Pb = -0.126 v
and {E^{0} H_{2}/ H^{+} = -0 v

Therefore, E^{0} cell = - 0.126 - 0 = -0.126 v

Since,  E^{0} cell is negative, hence cell reaction is non-spontaneous.

....................................................................................................................

Answer 3: 
Consider reaction: <span>2Ag^+ (aq) + Cr(s) ---> 2 Ag (s) +Cr^2+ (aq)
</span>
The cell representation of above reaction is given by;
    Cr/Cr^{2+} // Ag^{+}/Ag

Hence, E^{0}cell = E^{0} Ag^{+}/Ag - E^{0} Cr/Cr^{2+}
we know that, {E^{0} Ag^{+}/Ag = -0.22 v
and {E^{0} Cr/ Cr^{2+} = -0.913 v

Therefore, E^{0} cell = - 0.22 - (-0.913) = 0.693 v

Since,  E^{0} cell is positive, hence cell reaction is spontaneous
8 0
3 years ago
Read 2 more answers
An increase in the atomic number________the atomic radius moving from left to right across a period.
frez [133]

Answer:

decrease

Explanation:

Atomic radius :

It is the distance from the center of nucleus to the outer most electronic shell.

Trend along period:

As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required

4 0
3 years ago
Of these non-metals which one is likely to be least reactive
natulia [17]

Answer:

the answer is the swecond option

Explanation:

Its b ur well come

7 0
3 years ago
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