Glucose molality

Problem 24 80 grams of a simple sugar is added to 750 g of water. The sugar is glucose, with the composition QH Oe. What is the molality of glucose in the solution ... 

Figure 6.10 Effect of CITREM on the molecular and thermodynamic parameters of maltodextrin SA-2 (DE = 2) in aqueous medium (phosphate buffer, pH = 7.2, ionic strength = 0.05 M 20 °C) (a) weight average molar mass, Mw (b) radius of gyration, Ra (c) structure sensitive parameter, p, characterizing die architecture of maltodextrin associates (d) second virial coefficient, A2 or A2, on the basis of the weight ( ) and molal (A) scales, respectively. The parameter R is defined as the molar ratio of surfactant to glucose monomer units in the polysaccharide. The indicated cmc value refers to the cmc of the pure CITREM solution. Reproduced from Anokhina et al. (2007) with permission.

What is the molality of an aqueous glucose solution if the boiling point of the solution at 1 atm pressure is 101.27°C The molal boiling-point-elevation constant for water is given in Table 11.4. 

Let s calculate the molality of a solution prepared by dissolving 1.0 g of glucose in 20 g of water. Again, we start by finding the moles of glucose. 

But we can also answer this question by converting molarity to molality. So, what is the molal concentration of a 0.28 molar solution of glucose To convert between molality and molarity, we need to know the density of the solution. The density of a D5W solution is 1.0157 g/mL. We also need to be very careful about the definitions of molarity and molality, and keep in mind whether we are dealing with liters of solutions or kilograms of solvent. 

Step 1 Think about our goal. To find the molality of the solution, we need to find the number of moles of glucose and the kilograms of water in a sample of the solution. That is, we need values for x and y. 

The importance of M is unmistakable when it is recalled that 180 g glucose in 10s g water [1 molal (m)] lowers the freezing point by 1.86°C, whereas the same weight of polysaccharide (1.80 X 10 3 m, assuming M = 105 g) has no such effect and, moreover, it is difficult if not impossible to disperse 105 g of any polysaccharide in 103 g water. Identical arguments hold for boiling-point elevation and osmotic pressure. However, polysaccharides at much lower concentrations exercise influences, most prominently by... 

To maintain equal cell concentrations at equivalent levels of sucrose and CKlt amount of these substances required to give indicated molal concentration added to usual volume (3.45 ml.) of uptake buffer containing glucose and L-Cu-glutamic acid. Incubation for 100 minutes at37°C. Amount of glutamate calculated from isotope content of cell extracts... 

A solution of glucose (molecular weight 180.16) in water (molecular weight 18.01) is prepared. The mole fraction of glucose in the solution is 0.100. What is the molality of... 

The correct answer is (D). If the mole fraction of glucose is 0.100, that means that the mole fraction of water must be 1.00 - 0.100 = 0.900. Knowing this, you can determine the mass of the solvent, and from that the molality ... 

Notice that the equation calls for moles of dissolved particles. Ionic compounds can dissociate in solution and form a number of particles in solution. For example, if a 1.0-molal solution of NaCl were prepared, it would act as if it were 2.0 molal in nature. This is because every one mole of NaCl releases two moles of ions (Na+ and Cl-). This is a huge difference from a compound like glucose, C6H1206, where the atoms are covalently bonded and will not dissociate in solution. That means a 1.0-molal solution of glucose will be one molal in particles even though one mole of glucose has more atoms than one mole of NaCl has ions. 

The solution was prepared using 0.1500 kg of water. Using the definition of molality, we can find the number of moles of glucose in the solution. 

Figure 12 The complex permittivity of water and 2.8 molal aqueous glucose solution at 278 K O, t.d.s measurement of e water) , t.ds. measurement of e iyvater) ----------------------,., data interpolated from ref. 24 ...

Cl ). In practical terms, this means that a 1 molal solution of NaCl will have (approximately) twice the osmolality (osmotic pressure) as a 1 molal solution of glucose. 

The total osmolality or osmotic pressure of a solution is equal to the sum of the osmotic pressures or osmolalities of all solute species present. The electrolytes Na", Cr, and HCO3, which are present in relatively high concentration, make the greatest contribution to serum osmolality. Nonelectrolytes such as glucose and urea, which are present normally at lower molal concentrations, contribute less, and serum proteins contribute less than 0.5% of the total serum osmolality because even the most abundant protein is present at millimolar concentrations. 

Phase equilibria in water have been described by Kelly, who studied the effect of hexoses, sucrose, and inorganic salts on each other. The conclusion was reached that, for sucrose, the solubility of the second solute influences the composition at the invariant point, but for D-fructose, this effect is zero because of the high solubility of this sugar in water. Viscosity and density have also been evaluated at different temperatmes in methyl sulfoxide, and were fitted to appropriate equations by use of least-squares methods. The apparent molal volume calculated in this way is in perfect agreement with the theoretical data, whereas the differences for D-glucose and sucrose are 8 and 4%, respectively. 

Kb is the boiling point elevation constant, and for water equals 0.52°C/m. Each solvent has its own unique value for Kb, and the value of Kb for water indicates that a 1.0 m solution of glucose, a nonelectrolyte, would boil 0.52°C higher than that of pure water, 100.52°C. As with the equation used to calculate freezing point depressions, if the solute is an electrolyte, the molality of the ions will be a whole number multiple of the molality of the compound. 

The vapor pressure of a glucose (CgHx206) solution is 17.01 mmHg at 20°C, while that of pure water is 17.25 mmHg at the same temperature. Calculate the molality of the solution. 

Freezing-point depression is directly proportional to molality, so we first change the mole fraction of glucose to molality of glucose. Assuming that we have 1.0000 mol total, there are present 0.0555 mol of glucose and... 

Lemon juice is a complex solution that does not freeze in a home freezer at temperatures as low as — 11°C. At what temperature will the lemon juice freeze if its effective molality is the equivalent of a 10.48 m glucose solution ... 

Problem 7.16. What is the freezing point of a 0.100 m (molal) solution of glucose ... 

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