1.calculate the hydrogen concentration for each of the following.
(a).blood plasma, pH=7.4
(b).orange juice, pH=3.5
(c).human urine, pH=6.2
(c).gastric juice, pH=1.8
(d).household ammonia, pH=11.5
2. what buffer is used in the body system to preserve the following
a)urine
b)saliva
c)egg white
1. To calculate the hydrogen concentration (H+) for each solution, we can use the formula:
[H+] = 10^(-pH)
(a) Blood plasma, pH = 7.4
[H+] = 10^(-7.4)
[H+] ≈ 3.98 x 10^(-8) M
(b) Orange juice, pH = 3.5
[H+] = 10^(-3.5)
[H+] ≈ 3.16 x 10^(-4) M
(c) Human urine, pH = 6.2
[H+] = 10^(-6.2)
[H+] ≈ 1.58 x 10^(-7) M
(d) Gastric juice, pH = 1.8
[H+] = 10^(-1.8)
[H+] ≈ 1.58 x 10^(-2) M
(e) Household ammonia, pH = 11.5
[H+] = 10^(-11.5)
[H+] ≈ 3.16 x 10^(-12) M
2. The buffers used in the body system to preserve different substances are:
(a) Urine: The buffer system used in urine is the phosphate buffer system, which consists of the dihydrogen phosphate ion (H2PO4-) and hydrogen phosphate ion (HPO4^2-).
(b) Saliva: The buffer system used in saliva is the bicarbonate buffer system, which consists of the bicarbonate ion (HCO3-) and carbonic acid (H2CO3).
(c) Egg white: The buffer system used in egg white is the albumin buffer system, where the protein albumin acts as a buffer to maintain the pH stability.
2. What is the [𝐶𝐻_3 𝐶𝑂𝑂^− ]/[𝐶𝐻_3 𝐶𝑂𝑂𝐻] ratio in an acetate buffer at pH 5.00
The [𝐶𝐻_3 𝐶𝑂𝑂^− ]/[𝐶𝐻_3 𝐶𝑂𝑂𝐻] ratio in an acetate buffer can be determined using the Henderson-Hasselbalch equation:
𝑝𝐻 = 𝑝𝐾𝑎 + 𝑙𝑜𝑔 ([𝐶𝐻_3 𝐶𝑂𝑂^− ]/[𝐶𝐻_3 𝐶𝑂𝑂𝐻])
Given that pH = 5.00 and the pKa value for acetic acid is 4.76 (approximately), we can rearrange the equation to:
[𝐶𝐻_3 𝐶𝑂𝑂^− ]/[𝐶𝐻_3 𝐶𝑂𝑂𝐻] = 10^(𝑝𝐻 − 𝑝𝐾𝑎)
[𝐶𝐻_3 𝐶𝑂𝑂^− ]/[𝐶𝐻_3 𝐶𝑂𝑂𝐻] = 10^(5.00 - 4.76)
[𝐶𝐻_3 𝐶𝑂𝑂^− ]/[𝐶𝐻_3 𝐶𝑂𝑂𝐻] ≈ 1.78
Therefore, the [𝐶𝐻_3 𝐶𝑂𝑂^− ]/[𝐶𝐻_3 𝐶𝑂𝑂𝐻] ratio in the acetate buffer at pH 5.00 is approximately 1.78.
3. How would the following buffers differ in their capacity
a).0.01M 〖𝑁𝑎〗_2 𝐻𝑃𝑂_4 𝑎𝑛𝑑 0.01𝑀 𝑁𝑎𝐻_2 𝑃𝑂_4
b).0.1M 〖𝑁𝑎〗_2 𝐻𝑃𝑂_4 𝑎𝑛𝑑 0.1𝑀 𝑁𝑎𝐻_2 𝑃𝑂_4
c).1.0M 〖𝑁𝑎〗_2 𝐻𝑃𝑂_4 𝑎𝑛𝑑 1.0𝑀 𝑁𝑎𝐻_2 𝑃𝑂_4
The buffer capacity refers to the ability of a buffer solution to resist changes in pH when small amounts of acid or base are added. It is directly influenced by the concentration of the buffer components.
(a) 0.01M Na2HPO4 and 0.01M NaH2PO4 buffer:
The buffer capacity is relatively low in this case because the concentration of the buffer components is relatively low.
(b) 0.1M Na2HPO4 and 0.1M NaH2PO4 buffer:
The buffer capacity is higher in this case compared to (a) because the concentration of the buffer components is higher. Therefore, it can resist pH changes caused by the addition of small amounts of acid or base better.
(c) 1.0M Na2HPO4 and 1.0M NaH2PO4 buffer:
The buffer capacity is the highest in this case because the concentration of the buffer components is the highest. It can effectively prevent significant pH changes even with greater amounts of acid or base added.
how could you know that this is buffer pairs if you have been given a multiple choice question test? give some examples
In a multiple-choice question test, there are several indications that a pair of substances could be a buffer system. Some of these indications include:
1. The presence of both a weak acid and its conjugate base or a weak base and its conjugate acid in the given options. Buffer systems commonly consist of a weak acid/base and its conjugate pair.
Example:
Option A: HCl and NaCl (not a buffer pair)
Option B: H2CO3 and NaHCO3 (buffer pair)
Option C: HNO3 and NaNO3 (not a buffer pair)
Option D: HCN and NaCN (buffer pair)
In this example, options B and D contain a weak acid (H2CO3 and HCN) and their corresponding conjugate base (NaHCO3 and NaCN), making them potential buffer pairs.
2. The option includes a salt of a weak acid and a strong base or a salt of a weak base and a strong acid. Salt solutions can act as buffer systems to some extent.
Example:
Option A: NaOH and HCl (not a buffer pair)
Option B: Na2CO3 and HCl (buffer pair)
Option C: NH3 and HNO3 (not a buffer pair)
Option D: NH4Cl and NaOH (buffer pair)
In this example, options B and D contain a salt of a weak acid (Na2CO3) and a strong acid (HCl) or a salt of a weak base (NH4Cl) and a strong base (NaOH), making them potential buffer pairs.
It's important to keep in mind that other factors, such as pH values and concentrations, may also need to be considered to determine the presence of a buffer system accurately.
4. Calculate the [𝐻^+ ] 𝑎𝑛𝑑 [𝑁𝑂_3^( −) ] of a 0.175M solution of nitric acid, 𝑁𝐻𝑂_3^( −).
5. Calculate the hydroxide ion concentration in a 0.175 solution of HCl.
6. Calculate the hydrogen ion concentration in 0.01M solution of Ca(𝑂𝐻)_2
7. The ionisation constant of water is 𝐾_𝑤=1.00×10^(−13.60) at body temperature, 37^0 𝐶. 𝑊ℎ𝑎𝑡 𝑎𝑟𝑒 𝑡ℎ𝑒 𝐻_3 𝑂^+ 𝑎𝑛〖 𝑂𝐻〗^− concentrations at that temperature?
8. Calculate the pH of the following solutions at 25^0 𝐶:(𝑎)0.0028𝑀 𝐻𝐶𝑙, (𝑏)0.014 𝐻𝑁𝑂_3, (𝑐)0.00052𝑀 𝐻𝐵𝑟,
0.092𝑀 𝐻𝐼
9. Calculate the pH of a 0.025M solution of ammonia, 𝐾_𝑏=1.75× 10^(−5)
4. To calculate the [𝐻^+ ] and [𝑁𝑂_3^(-) ] of a 0.175M solution of nitric acid, 𝑁𝐻𝑂_3^(-), we need to consider the dissociation of nitric acid in water:
𝑁𝐻𝑂_3 -> 𝐻^+ + 𝑁𝑂_3^(-)
Since nitric acid is a strong acid, it will completely dissociate in water. Therefore, the initial concentration of 𝐻^+ ions will be equal to the initial concentration of nitric acid, which is 0.175M. The concentration of 𝑁𝑂_3^(-) ions will be zero since it is a spectator ion and does not participate in the formation of additional 𝑁𝐻𝑂_3 molecules.
[𝐻^+ ] = 0.175M
[𝑁𝑂_3^(-) ] = 0M
5. In a 0.175M solution of HCl, HCl is a strong acid that will dissociate completely in water:
𝐻𝐶𝑙 -> 𝐻^+ + 𝐶𝑙^(-)
Since HCl is a strong acid, the initial concentration of 𝐻^+ ions will be equal to the initial concentration of HCl, which is 0.175M. The concentration of hydroxide ions (OH-) in this acidic solution will be negligible.
[𝐻^+ ] = 0.175M
[𝑂𝐻^- ] ≈ 0M
6. In a 0.01M solution of Ca(OH)2, Ca(OH)2 is a strong base that will dissociate completely in water:
Ca(OH)2 -> 2𝑂𝐻^- + 𝐶𝑎^2+
Each Ca(OH)2 molecule dissociates to produce two hydroxide ions (OH-), and the concentration of hydroxide ions will be twice the initial concentration of Ca(OH)2.
[𝐻^+ ] ≈ 0M
[𝑂𝐻^- ] = 2 * 0.01M = 0.02M
7. The ionization constant of water, 𝐾_𝑤, can be expressed as:
𝐾_𝑤 = [𝐻_3𝑂^+ ]*[𝑂𝐻^- ]
At body temperature, 37°C, the value of 𝐾_𝑤 is 1.00 x 10^(-13.60). To determine the concentrations of [𝐻_3𝑂^+ ] and [𝑂𝐻^- ], you would need to calculate the square root of 𝐾_𝑤 since the concentration of [𝐻_3𝑂^+ ] and [𝑂𝐻^- ] will be equal:
[𝐻_3𝑂^+ ] = [𝑂𝐻^- ] = 𝐾_𝑤^(0.5) = (1.00 x 10^(-13.60))^(0.5)
Simply calculate the square root of 𝐾_𝑤 to determine the concentrations at body temperature.
8. To calculate the pH of the following solutions at 25°C:
(a) 0.0028M HCl:
Since HCl is a strong acid that dissociates completely, the concentration of H+ ions will be equal to the initial concentration of HCl. Use the formula for pH:
pH = -log[H+]
pH = -log(0.0028)
(b) 0.014M HNO3:
Since HNO3 is also a strong acid that dissociates completely, the concentration of H+ ions will be equal to the initial concentration of HNO3. Use the formula for pH:
pH = -log[H+]
pH = -log(0.014)
(c) 0.00052M HBr:
HBr is a strong acid, so the concentration of H+ ions will be equal to the initial concentration of HBr. Use the formula for pH:
pH = -log[H+]
pH = -log(0.00052)
(d) 0.092M HI:
HI is a strong acid, so the concentration of H+ ions will be equal to the initial concentration of HI. Use the formula for pH:
pH = -log[H+]
pH = -log(0.092)
9. To calculate the pH of a 0.025M solution of ammonia, use the given Kb value:
Kb = [OH-][NH4+]/[NH3]
Since ammonia (NH3) is a weak base, we can assume that the concentration of [OH-] is negligible compared to [NH3]. Therefore, we can simplify the equation to:
Kb ≈ [OH-] * [NH4+]/[NH3]
To determine [OH-] concentration, you can use the equation:
[OH-] = Kb * [NH3]/[NH4+]
Then convert [OH-] to pOH:
pOH = -log[OH-]
Finally, calculate the pH:
pH = 14 - pOH
To calculate the hydrogen concentration (H+) for each of the given substances based on pH, you can use the following equation:
H+ concentration = 10^(-pH)
1. Hydrogen concentration calculation:
(a) Blood plasma, pH = 7.4
H+ concentration = 10^(-7.4)
(b) Orange juice, pH = 3.5
H+ concentration = 10^(-3.5)
(c) Human urine, pH = 6.2
H+ concentration = 10^(-6.2)
(d) Gastric juice, pH = 1.8
H+ concentration = 10^(-1.8)
(e) Household ammonia, pH = 11.5
H+ concentration = 10^(-11.5)
2. Buffers used in the body system to preserve substances:
(a) Urine: The buffer used in urine is primarily ammonium chloride (NH4Cl). It helps to maintain the pH of urine within a certain range to prevent excessive changes.
(b) Saliva: The buffer used in saliva is a mixture of bicarbonate ions (HCO3-) and phosphate ions (HPO42-). These ions help maintain the pH balance in the mouth, preventing tooth decay and promoting the breakdown of food.
(c) Egg white: The buffer used in egg white is primarily phosphate buffer, composed of various phosphate salts. This buffer system maintains the pH level within a suitable range to preserve the proteins and prevent degradation.