Using incorrect concentrations. If your vitamin C standard solution is too concentrated or your iodine titration solution is too diluted, or your starch indicator solution is not between 0.5 to 1.0%, it may require much more than 50 mL of iodine solution to titrate the standard solution and/or orange juice.
The following summarizes some common causes of fatigue but is not meant to be comprehensive: Metabolic/endocrine: anemia; hypothyroidism; diabetes; electrolyte abnormalities; kidney disease; liver disease; Cushing's disease.
At some point, nearly everyone suffers from fatigue. In most cases, it's acute fatigue -- fatigue that occurs suddenly but lasts less than three months and is usually caused by lifestyle or environmental factors such as physical exertion, stress, lack of sleep, dehydration, or inadequate diet.