Read More
Date: 24-1-2017
1260
Date: 19-7-2017
1530
Date: 16-4-2017
1138
|
The Effect of Temperature on Volume Measurements
The volume occupied by a given mass of liquid varies with temperature, as does the device that holds the liquid during measurement. Most volumetric measuring devices are made of glass, which fortunately has a small coefficient of expansion. Thus, variations in the volume of a glass container with temperature need not be considered in ordinary analytical work.
The coefficient of expansion for dilute aqueous solutions (approximately 0.025%/°C) is such that a 5°C change has a measurable effect on the reliability of ordinary volumetric measurements.
Example
A 40.00-mL sample is taken from an aqueous solution at 5°C. What volume does it occupy at 20°C?
V20° = V5° + 0.00025(20 - 5)(40.00) = 40.00 + 0.15 = 40.15 mL
Volumetric measurements must be referred to a standard temperature, often 20°C. The ambient temperature of most laboratories is usually close enough to 20°C so that there is no need for temperature corrections in volume measurements for aqueous solutions. In contrast, the coefficient of expansion for organic liquids may be large enough to require corrections for temperature differences of 1°C or less.
|
|
إجراء أول اختبار لدواء "ثوري" يتصدى لعدة أنواع من السرطان
|
|
|
|
|
دراسة تكشف "سببا غريبا" يعيق نمو الطيور
|
|
|
|
جامعة الكفيل تناقش تحضيراتها الخاصة بالامتحانات النهائية
|
|
المجمع العلمي يستأنف برنامج (عرش التلاوة) الوطني
|
|
أرباح مصرف الراجحي ترتفع إلى 4.4 مليار ريال في الربع الأول
|
|
الأمانة العامة للعتبة العبّاسية تشارك في مُلتقى أمناء العتبات المقدّسة داخل العراق
|