CHE330 F23 HW2 Solved

CHE330, Fall 2023 HW#2 1 Discussion of HW and working together with others is encouraged for homework assignments. Talking it through often helps comprehension. However, this does not include copying of someone else’s work. Please write out the sentence below on your homework assignment followed by your signature to affirm that you did not copy or use someone else’s work. “I affirm that I have upheld my own integrity and that of the university on this assignment” followed by your signature. Show your work for full credit. Include units for all values (if appropriate) and use correct number of significant figures in your answers. Insert graphs into your homework solution and also submit the excel file in which it was generated (or other software program file used). Problem 1: Viscometer data of honey [12] Viscometers are instruments designed to measure the viscosity of a fluid. Imagine a viscometer that applies a shear (tangential force) to a fluid, and measures the force required to apply this shear (the shear stress). Example data from a viscometer is shown below, where the shear stress as a function of the velocity gradient (here, the rate of shear strain) is tabulated. The data below is for different types of honey adapted from: Santos, Francisco Klebson & Filho, Antonio & Leite, R.H.L. & Aroucha, Edna & Santos, Andarair & Oliveira, Thiago. (2014). Rheological and some physicochemical characteristics of selected floral honeys from plants of caatinga. Anais da Academia Brasileira de Ciências. 86. 10.1590/0001-3765201420130064. Shear stress as a function of strain rate for different types of honey shear rate (1/s) shear stress (Pa) croton camprestris cobretum leprosum mimosa tenufiora 0 0 0 0 10 18 48 88 20 40 105 178 30 52 149 249 40 60 199 344 50 91 255 420 60 105 310 520 70 130 351 597 80 145 385 669 90 170 444 771 a. [5] Plot the data on a graph of shear stress as a function of shear rate. Since you have individual data points, plot individual points. You may use any type of software, but Excel is

CHE330, Fall 2023 HW#2 2 recommended. Make sure your plot shows data points, legend, and has labelled axes including units. b. [2] What type of fluid is honey (Newtonian, shear thinning, shear thickening)? Explain your answer using your graph. Newtonian – linear slope (ex. Increasing shear stress with increasing shear rate) c. [5] If a fluid is Newtonian, you can fit a linear trendline through the data from part a, forcing the intercept through the origin. Show the trendline and the equation of the trendline on the plot (note that the intercept of the trendline must be zero- you can force it through zero in the trendline setup in Excel). Determine the viscosity of each type of honey in cP. 0 200 400 600 800 1000 0 20 40 60 80 100 Shear Stress (Pa) Shear Rate (1/s) croton camprestris cobretum leprosum mimosa tenufiora y = 1.8172x R² = 0.9974 y = 4.9716x R² = 0.9994 y = 8.5112x R² = 0.9998 0 100 200 300 400 500 600 700 800 900 0 20 40 60 80 100 Shear Stress (Pa) Shear Rate (1/s) croton camprestris cobretum leprosum mimosa tenufiora Linear (croton camprestris) Linear (cobretum leprosum) Linear (mimosa tenufiora)