Based on the test results, the differences of the carbonized depth of concrete measured by phenolphthalein indicator and rainbow indicator were discussed, the effects of the water to cement ratio of concrete, the carb...Based on the test results, the differences of the carbonized depth of concrete measured by phenolphthalein indicator and rainbow indicator were discussed, the effects of the water to cement ratio of concrete, the carbonized age and the relative humidity of environment on the carbonized depth of concrete and the depth of half-carbonized zone corresponding to green zone measured by rainbow indicator were also analyzed. It is proved that the depth measured by phenolphthalein indicator is always smaller than that measured by rainbow indicator, and the half-carbonized zone can only be measured by rainbow indicator. The carbonized and half-carbonized depths of concrete are influenced by the carbonation age, the water to cement ratio of concrete and the relative humidity of environment. It is suggested that the phenolphthalein indicator can be used to measure the carbonized depth of concrete when the strength grade of concrete is below C45, otherwise, the rainbow indicator should be utilized.展开更多
Acid-Base Indicator, Turmeric Rhizome (Curcuma longa) was extracted from the root of a turmeric plant. The turmeric was peeled, washed and dried in an oven at 60°C. It was ground into powder and soaked in hot ...Acid-Base Indicator, Turmeric Rhizome (Curcuma longa) was extracted from the root of a turmeric plant. The turmeric was peeled, washed and dried in an oven at 60°C. It was ground into powder and soaked in hot and cold ethanol for the extraction. The extract was filtered and part of it was concentrated to yield a reasonable quantity of turmeric indicator. On standardization of acid with a base, 0.05 M base respectively of Sodium hydroxide (NaOH), sodium carbonate (Na<sub>2</sub>CO<sub>3</sub>) and Disodium borate (B<sub>4</sub>Na<sub>2</sub>O<sub>7</sub>) were used. Hot and cold extracts of turmeric were used as indicators and were compared with methyl orange and phenolphthalein. On the preliminary test carried out, hot and cold turmeric indicator showed yellow colour in acid medium and orange colour in the base. Methyl orange showed red colour in acid but yellow in the base, phenolphthalein was colourless in acid but pink in the base. During titration there were colour changes at the end points in the entire test carried out. The average volumes at ends points were calculated, the molar concentrations and mass concentrations of the acids used were also determined. The results showed that there was no difference between the natural indicators used and the existing synthetic indicators which are toxic to our environment.展开更多
基金Funded by Outstanding Youth Science Foundation of Henan Province of China (No. 04120002300)
文摘Based on the test results, the differences of the carbonized depth of concrete measured by phenolphthalein indicator and rainbow indicator were discussed, the effects of the water to cement ratio of concrete, the carbonized age and the relative humidity of environment on the carbonized depth of concrete and the depth of half-carbonized zone corresponding to green zone measured by rainbow indicator were also analyzed. It is proved that the depth measured by phenolphthalein indicator is always smaller than that measured by rainbow indicator, and the half-carbonized zone can only be measured by rainbow indicator. The carbonized and half-carbonized depths of concrete are influenced by the carbonation age, the water to cement ratio of concrete and the relative humidity of environment. It is suggested that the phenolphthalein indicator can be used to measure the carbonized depth of concrete when the strength grade of concrete is below C45, otherwise, the rainbow indicator should be utilized.
文摘Acid-Base Indicator, Turmeric Rhizome (Curcuma longa) was extracted from the root of a turmeric plant. The turmeric was peeled, washed and dried in an oven at 60°C. It was ground into powder and soaked in hot and cold ethanol for the extraction. The extract was filtered and part of it was concentrated to yield a reasonable quantity of turmeric indicator. On standardization of acid with a base, 0.05 M base respectively of Sodium hydroxide (NaOH), sodium carbonate (Na<sub>2</sub>CO<sub>3</sub>) and Disodium borate (B<sub>4</sub>Na<sub>2</sub>O<sub>7</sub>) were used. Hot and cold extracts of turmeric were used as indicators and were compared with methyl orange and phenolphthalein. On the preliminary test carried out, hot and cold turmeric indicator showed yellow colour in acid medium and orange colour in the base. Methyl orange showed red colour in acid but yellow in the base, phenolphthalein was colourless in acid but pink in the base. During titration there were colour changes at the end points in the entire test carried out. The average volumes at ends points were calculated, the molar concentrations and mass concentrations of the acids used were also determined. The results showed that there was no difference between the natural indicators used and the existing synthetic indicators which are toxic to our environment.
