Pick the compound with a higher percent lonic character than KCI. (MgF ; SrCl ; NaF ; CaBr)

Calcium hydride reacts with water to form hydrogen gas and calcium hydroxide. How many grams of calcium hydride are needed to ge

4vir4ik [10]

The Equation is CaH2(s)+2H2O(l)-->Ca(OH)2(aq)+2H2(g)

so,

moles of H2 generated = PV / RT

R = 62.363 L Torr K−1 mol−1

number of moles = 814 * 53.5 / 62.363 * 293

= 2.38 moles

looking at the equation these came from 2.38 /2 moles of CaH2 or 1.19 moles

Molar mass of CaH2 is 42.0943 g/mol

so mass of CaH2 = 1.19 X 42.1 = 50.01g

3 0

3 years ago

A solution has a pH of 2.5. what is the H+

romanna [79]

Answer: The concentration of $H^+$ in the solution is $3.16\times 10^{-3}M$

Explanation:

pH is defined as the negative logarithm of hydrogen ion concentration present in the solution.

$pH=-\log [H^+]$ .....(1)

We are given:

pH of solution = 2.5

Putting values in equation 1, we get:

$2.5=-\log [H^+]$

$[H^+]=10^{-2.5}$

$[H^+]=3.16\times 10^{-3}M$

Hence, the concentration of $H^+$ in the solution is $3.16\times 10^{-3}M$

4 0

3 years ago

A solution is prepared by mixing 25 mL pentane (C3H12, d =

defon

Hope this helps you with yoyrslef

7 0

3 years ago

A Bronsted-Lowry acid is defined as a substance that ________. A Bronsted-Lowry acid is defined as a substance that ________. in

Anestetic [448]

Answer: A Bronsted-Lowry acid is defined as a substance that acts as a proton donor.

Explanation:

A substance that is able to donate a proton or hydrogen ion to another substance is a Bronsted-Lowry acid.

For example, HCl is a Bronsted-Lowry acid as it dissociates to give a hydrogen ion.

$HCl \rightleftharpoons H^{+} + Cl^{-}$

Thus, we can conclude that a Bronsted-Lowry acid is defined as a substance that acts as a proton donor.

3 0

3 years ago

(b) Which peak, the one at 365 nm or the one at 435 nm, results from the absorption of

GenaCL600 [577]

Answer:

365nm and Exothermic reaction

Explanation:

b) The Einstein Planck's equation states that

E = hf where E is the energy of a photon

h is the Planck's constant

f is the frequency

But Frequency f = c/λ where c is the speed of light

λ is the wavelength

Therefore Energy E = hc/λ

From the above equation we see that the Energy of a photon is indirectly proportional to its wavelength

Hence as the wavelength increases from 365nm to 435nm, the energy of the photons decreases

Therefore, a photon will wavelength 365nm would have a higher energy than one will wavelength of 435nm.

c) From the diagram we observe the following:

At high temperatures, HPR⁺ occurs at a higher concentration than at low temperatures.

At low temperatures, more of PR⁻ is formed than at high temperatures

The equation of the reaction is

HPR⁺ (aq) ⁺ ⇆ H⁺ + PR⁻(aq)

Le Chartelier's principle states that when an external constraint such as a change in concentration, pressure or temperature is placed on a system in equilibrium, the system acts in such a way as to oppose the change.

Hence a decrease in temperature on the side of reactant, HPR would force the equilibrium to the side of the products, PR in other to accommodate the change

The forward reaction, which produces more of the product PR⁻ is exothermic because the at low temperatures, the the forward reaction is favoured and equilibrium shifts to the right.

5 0

3 years ago