A melting point of a sample of Urea was completed and a melting range of 122-128 °C was observed and recorded. The accepted-literature value for the melting point of Urea is 133-135 °C. Calculate the percent error of the melting point compared to the literature value for the Urea. Only include the number in your answer. Do not include the + or - signs in the answer or the % unit sign.

In a lab investigation, a student is asked to crush and measure 1 g of sulfur from a larger solid block. The student understands that although the mass of the sample is changing, the melting point will remain the same because he/she knows that ___.

Why is fractional distillation more efficient than simple distillation when purifying liquid mixtures?

Given the following: Solutions Flask 1 Flask 2 Flask 3 0.04 M KI 25.0 mL 25.0 mL 12.5 mL 1% starch 5.00mL 5.00mL 5.00mL 0.03 M Na2S2O3 5.50 mL 5.50 mL 5.50 mL 0.05 M H2SO4 5.00 mL 5.00mL 5.00mL 0.08 M NaCl 0 0 10.0 mL and Solutions Beaker 1 Beaker 2 Beaker 3 0.04 M H2O2 25.0 mL 12.5 mL 25.0 mL deioinized water 0 12.5 mL 0 Following the procedure Run 1 is when Beaker 1 is added to Flask 1 and the timer is started giving the time recorded for the run in the table below.  This is repeated with Beaker 2 and Flask 2 for Run 2 and finally Beaker 3 and Flask 3 for Run 3: The results for these runs are given below: Run Time (seconds) 1 35 2 66 3 72  Calculate the following for each run: the initial molarities of I- and H2O2 (from the solutions tables) the rates of reaction [I2]/time (calculate the [I2] from [S2O32-] and the reaction: I2(aq) + 2 S2O32-(aq)  →   2I-(aq) + S4O62-(aq) Choose the correct rate law for this reaction from your calculations.…

Only typed solution.

5. Use the date reported below to graph a cooling plot and use the graphical method to calculate the freezing point of the substance. Is this a pure substance or a solution? t (min) 1 2 3 6 7 8 T (°C) 55.6 51.1 46.7 42.2 37.8 33.3 28.9 31.4 t (min) 9 10 11 12 13 14 15 16 T (°C) 30 28.6 27.1 25.7 24.3 22.86 21.6 20

Using this percent change data, determine the concentration of sucrose that would be isotonic. You do not have to be exact  Isotonic concentration = ______________________ M 0.0 M sucrose = 0.24/4.6x100=5.2%%  0.4 M sucrose = 0.39/4.59x100=8.4% 0.6 M sucrose = 0.70/4.7x100=14.8%  0.8 M sucrose =0.80/4.5x100=17%  1.0 M sucrose =1/5x100=20%

How do you find the freezing point of t-Butanol?

Refer to the numbered stages in the image above. How does the membrane permeability to Na+ and K+ change during depolarization, repolarization, and hyperpolarization? Place the blue markers in order from 1-5.

What are the differences between a simple distillation and steam distillation?