Biology question 1.Cyanidium caldarium is a type of red algae that only grows in
ID: 56657 • Letter: B
Question
Biology question
1.Cyanidium caldarium is a type of red algae that only grows in solutions with a pH of less than 1. A microbiologist makes a solution by adding 5.9 g HCl to 1 L of water. HCl is a strong acid with a molecular weight of 34.5 g/mol. What will the pH of this solution be?
2.R: Escherichia coli and Helicobacter pylori are well-known pathogenic bacteria that can survive in low pH environments, generally < 3. The H+ concentration in the stomach of an average adult human is 50 mM. What is the pH of the human stomach? In contrast, the H+ concentration in the stomach of a cow is 0.001 mM. What is it’s pH?
Explanation / Answer
1.Cyanidium caldarium is a type of red algae that only grows in solutions with a pH of less than 1. A microbiologist makes a solution by adding 5.9 g HCl to 1 L of water. HCl is a strong acid with a molecular weight of 34.5 g/mol. What will the pH of this solution be?
Calculating pH
To calculate the pH of an aqueous solution you need to know the concentration of the hydronium ion in moles per liter (molarity). The pH is then calculated using the expression:
pH = - log [H3O+].
First we need to find the concentration (or) Molarity of the HCL by using the following formula.
Molarity=Weight/Molecular weight*1000/V in ml
M=5.9/34.5*1000/1000 (5.9 g HCl to 1 L (or) 1000ml of water.)
M=0.1710
pH = - log [H3O+]
pH = - log [0.1710]
pH = - (-0.7670039)
pH =0.7670039
2.R: Escherichia coli and Helicobacter pylori are well-known pathogenic bacteria that can survive in low pH environments, generally < 3. The H+ concentration in the stomach of an average adult human is 50 mM. What is the pH of the human stomach? In contrast, the H+ concentration in the stomach of a cow is 0.001 mM. What is it’s pH?
The H+ concentration in the stomach of an average adult human is 50 mM
convert H+ concentration to Molarity=50*10-3=0.05M
Using pH = - log [H3O+]
pH = - log [0.05]
pH = 1.30
H+ concentration in the stomach of a cow is 0.001 mM=0.001*10-3M=.000001M
Using pH = - log [H3O+]
pH = - log [0.000001]
pH = - log [0.000001]
pH = - log [-6]
pH = 6
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