They are a relatively recent invention.
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Elemental copper would be a pure substance.
Answer:
C) 1 x 10-10 M
Explanation:
To solve this question we must use the equation:
Kw = [H+] [OH-]
<em>Where Kw is the equilibrium dissociation of water = 1x10-14</em>
<em>[H+] is the molar concentration of hydronium ion = 1x10-4M</em>
<em>[OH-] is the molar concentration of hydroxyl ion</em>
<em />
Replacing:
1x10-14= 1x10-4 [OH-]
<em>[OH-] = 1x10-14 / 1x10-4M</em>
<em>[OH-] = 1x10-10 M</em>
Right option is:
<h3>C) 1 x 10-10 M
</h3>
Answer:
676mmHg
Explanation:
Using the formula;
P1/T1 = P2/T2
Where;
P1 = initial pressure (mmHg)
P2 = final pressure (mmHg)
T1 = initial temperature (K)
T2 = final temperature (K)
According to the information provided in this question;
P1 = 725.0mmHg
P2 = ?
T1 = 20°C = 20 + 273 = 293K
T2 = 0°C = 0 + 273 = 273K
Using P1/T1 = P2/T2
725/293 = P2/273
Cross multiply
725 × 273 = 293 × P2
197925 = 293P2
P2 = 197925 ÷ 293
P2 = 676mmHg.
The resulting pressure is 676mmHg
a. pH=2.07
b. pH=3
c. pH=8
<h3>Further explanation</h3>
pH=-log [H⁺]
a) 0.1 M HF Ka = 7.2 x 10⁻⁴
HF= weak acid
![\tt [H^+]=\sqrt{Ka.M}\\\\(H^+]=\sqrt{7.2.10^{-4}\times 0.1}\\\\(H^+]=8.5\times 10^{-3}\\\\pH=3-log~8.5=2.07](https://tex.z-dn.net/?f=%5Ctt%20%5BH%5E%2B%5D%3D%5Csqrt%7BKa.M%7D%5C%5C%5C%5C%28H%5E%2B%5D%3D%5Csqrt%7B7.2.10%5E%7B-4%7D%5Ctimes%200.1%7D%5C%5C%5C%5C%28H%5E%2B%5D%3D8.5%5Ctimes%2010%5E%7B-3%7D%5C%5C%5C%5CpH%3D3-log~8.5%3D2.07)
b) 1 x 10⁻³ M HNO₃
HNO₃ = strong acid
![\tt pH=-log[1\times 10^{-3}]=3](https://tex.z-dn.net/?f=%5Ctt%20pH%3D-log%5B1%5Ctimes%2010%5E%7B-3%7D%5D%3D3)
c) 1 x 10⁻⁸ M HCl
![\tt pH=-log[1\times 10^{-8}]=8](https://tex.z-dn.net/?f=%5Ctt%20pH%3D-log%5B1%5Ctimes%2010%5E%7B-8%7D%5D%3D8)
