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Why do mixtures of acetone and chloroform exhibit significant negative deviations from Raoult's law?
Wiki User
∙ 13y ago
This is because chloroform can hydrogen bond with acetone
Wiki User
∙ 13y ago
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Why is an increase in temperature observed on mixing chloroform with acetone?
The enthalpy of mixing for this mixture is negative: and the mixing is an exothermic process in this case.
What is the value of G for a reaction that is spontaneous?
The value isn't significant, but ∆G must be negative for a spontaneous reaction.
Why is chloroform used in DNA extraction?
MgCl2 is used to preserve the integrity of membrane system by counteracting the fixed negative charges of membrane phospholipid. Depending on what you want to extract, it tries to protect the component you are interested in (DNA/RNA/red blood cells, etc) from being lyzed by broken-open lysosome for instance.
Why use negative ions in mass spec?
Mass spec is done as a mass to charge ratio (m/z), so encouraging the compounds to have the same charge (by adding a bit of a low MW acid, for example ) is helpful in interpretation. You also have to do a calibration after setting the charge. Positive ionization has been most common, and is used for peptides and proteins. Oligosaccharides, nucleotides and a few metals are typically done with negative ionization because their pKas are high and so it is more difficult to get positive ionization on them. Sometimes negative ion MS is used for mixtures because the abundance of the negative forms are lower and so the mixture is simpler to first analyze that way.
What resources do coal fired power stations use?
The most significant resource that a coal fired power station uses is of course coal. Coal is a non renewable natural resource and mining of coal has significant negative effects. In many cases coal is mined in sensitive grassland and wetland habitats - causing significant water pollution. Power stations also rely on large amounts of freshwater in the cooling towers as part of the power production process.
Can the standard deviation or variance be negative?
No, a standard deviation or variance does not have a negative sign. The reason for this is that the deviations from the mean are squared in the formula. Deviations are squared to get rid of signs. In Absolute mean deviation, sum of the deviations is taken ignoring the signs, but there is no justification for doing so. (deviations are not squared here)
In any distribution is the sum of the squared deviations from the mean always equal to zero?
No. It cannot be. Remember that when you square a negative number it becomes a positive number. Thus all squared deviations are positive and their sum must be positive.
Why is an increase in temperature observed on mixing chloroform with acetone?
The enthalpy of mixing for this mixture is negative: and the mixing is an exothermic process in this case.
The sum of the deviations from the mean is always zero?
The definition of the mean x of a set of data is the sum of all the values divided by the total number of observations, and this value is in turn subtracted from each x value to calculate the deviations. When the deviations from the average are added up, the sum will always be zero because of the negative signs in the sum of deviations. Going back to the definition of the mean, the equation provided (x = Σxi/n) can be manipulated to read Σxi - x = 0
How does a weatherman use positive and negative numbers?
He could use them is describing temperatures. Or deviations from historical averages for rainfall, hours of sunshine, and so forth.
Why we called as excess molar volume?
There are idealand non-ideal mixtures. In the second case the intermolecular forces between the different molecules of the mixture are less (Positive deviations from Raoult's Law) or more (Negative deviations from Raoult's Law) strong than they are in the pure liquids.This difference in the intermolecular forces causes a expansion (less strong) or retraction (more strong) of the volume after the mixing, this is the cause of the excess molar volume.The excess molar volumes VE can be calculated by using measured experimental densities and correlated by the Redlich−Kister type equation.
Why do you square the deviations to get the variance and then take the reverse action of taking the square root of the variance to return the variance to sigma?
because of two things- a) both positive and negative deviations mean something about the general variability of the data to the analyst, if you added them they'd cancel out, but squaring them results in positive numbers that add up. b) a few larger deviations are much more significant than the many little ones, and squaring them gives them more weight. Sigma, the square root of the variance, is a good pointer to how far away from the mean you are likely to be if you choose a datum at random. the probability of being such a number of sigmas away is easily looked up.
Are gram negative rods significant in throat swab cultures?
no
What are the negative effects of Diwali on the environment?
The Hindu Festival of Lights, Diwali, has no known significant negative effects on the environment.
What is the probability of randomly selecting values more then 2.57 standard deviations away from the mean in either a positive or negative direction in a normal distribution?
1% total 0.5% in either direction
What does a correlation factor of -0.95 mean?
This means that the correlation is negative but still significant.
How many significant figures are there in 2.54 times 10 negative 5 liters?
3
