1. 15.8 g of KCl is dissolved in 225 mL of water. Calculate the molarity. 2. Calculate the mass of KCl required to prepare 250. mL of 0.250 M solution.
| Object | Estimated Mass (g) | Actual Mass (g) | Actual Mass (kg) | Pen or pencil | 5 | 5.4 | .0054 | 3 Pennies | 6 | 7.6 | .0076 | 1 Quarter | 5 | 5.7 | .0057 | 2 Quarters, 3 Dimes | 15 | 18.2 | .0182 | 4 Dimes, 5 Pennies | 15 | 21.6 | .0216 | 3 Quarters, 1 Dime, 5 Pennies | 25 | 31.9 | .0319 | Key | 10 | 9.2 | .0092 | Key, 1 Quarter, 4 Pennies | 20 | 24.9 | .0249 | Data Table 4: Liquid measurements. | | | Mass A | Mass B | Mass B - A | | | Liquid | Volume(mL) | GraduatedCylinder (g) |
Laboratory Techniques and Measurements – Lab Report Assistant Exercise 1: Length, Temperature, and Mass Data Table 1. Length Measurements Object Length (cm) Length (mm) Length (m) CD or DVD 11.7 116.8 0.1 Key 6.1 61.0 0.1 Spoon 14.5 144.8 0.1 Fork 17.0 170.2 0.2 Data Table 2. Temperature Measurements Water Temperature (°C) Temperature (°F) Temperature (K) Hot from tap 65.1 149.2 338.3 Boiling 97.5 207.5 370.7 Boiling for 5 minutes 100.0 212.0 373.2 Cold from tap 23.0 73.4 296.2 Ice water – 1 minute 7.8 46.0 281.0 Ice water – 5 minutes 4.0 39.2 277.2 Data Table 3. Mass Measurements Object Estimated Mass (g) Actual Mass (g) Actual mass (kg) Pen or pencil 7.5 10.7 0.01 3 Pennies 8.0 7.4 0.007 1 Quarter 3.0 5.6 0.006 2 Quarters, 3 Dimes 15.7 18.2 0.02 4 Dimes, 5 Pennies 20.9 21.5 0.02 3 Quarters, 1 Dime, 5 Pennies 29.4 31.7 0.03 Key 8.6 10.0 0.01 Key, 1 Quarter, 4 Pennies 25.0 25.7 0.03 Questions: A) Water boils at 100°C at sea level. If the water in this experiment did not boil at 100°C, what could be the reason?
Laboratory Techniques and Measurements Purpose: Learn about the various types of measurements such as gram, milliliter, centimeter, cm^3, Celcius, and Kelvin and how they translate into other forms of measurement. Procedure: Take various measurements Data Tables: |Data Table 1: Length measurements. | |Object |Length (cm) |Length (mm) |Length (m) | |CD or DVD |12 |120 |.12 | |Key |5.2 |52 |.052 | |Spoon |17.3 |173 |.173 | |Fork |17.7 |177 |.177 | |Data Table 2: Temperature measurements. | |Water |Temperature (°C) |Temperature (°F) |Temperature (K) | |Hot from tap |41 |105.8 |314.15 | |Boiling |97 |206.6 |370.15 | |Boiling for 5 minutes |100 |212 |373.15 | |Cold from tap |25
A. 0.420 M B. 0.567 M C. 0.042 M D. 0.325 M _____ 3. What is the freezing point of an aqueous glucose solution that has 25.0 g of glucose, C6H12O6, per 100.0 g of H2O ? (Kf for water = 1.86 °C /m) A.
Also include any observations that you made over the course of part II. (4 points) Unknown (A,B,C,D) Mass of Metal Volume of water Initial temp. in calorimeter Initial temp. in beaker Final temp. of mixture Metal C 25.605g 24.6mL 25.2°C 100.5°C 28.7°C Calculations: Show your work and write a short explanation with each calculation.
Prelaboratory preparation: Read pages 1 – 30 and 45 – 54 of the lab text. You may disregard the microscale distillation procedures of TECH 0704. Answer in your laboratory notebook the Safety Quiz on pages 11 – 12 and the Prelab Questions 1, 2a, 2b, 3 -5, pp. 67 - 68. EXPERIMENT: TECH 0704, Distillation, macroscale technique only, simple and fractional: Substitute a mixture of 25 mL ethanol and 25 mL water for the toluene/cyclohexane mixture.
5. Repeat until the mass is consistent. Data and Observations: Measured melting point | 93.0 ̊ C | Real melting point | 92.5 ̊ C | Mass of evaporating dish | 47.01 g | Mass of evaporating dish and crushed alum | 49.13 g | Mass of crushed alum | 2.12 g | Mass after 1st heating | 48.17 g | Mass after 2nd heating | 48.16 g | Mass of water driven off | .97 g | Mass of anhydrous alum | 1.15 g | Moles of H2O | .0539 moles | Moles of AlK(SO4)2 | .0045 moles | Mole ratio; H2O/AlK(SO4)2 | 12.0 | During the heating of the crushed alum in the hot water bath, the alum had liquefied. The boiling point temperature that was determined was 93.0 degrees Celsius. This process had taken a long time, but around 90 degrees
93 g/mol? Not we get to use it! Yay! 93 g/mol / 31.06 g/mol = 3 (this is the multiplier) Multiply that whole number through the subscripts of the empirical formula. 3 x (C H5 N) = C3H15N3 Hydrated compounds Solving process: 1st- the difference between the initial mass and that of the dry sample is the mass of water that was driven off.
The Density of Solids and Liquids By: Maxwell Coulter Date: September 16 2013 Partners: Joey Kraczs, Liz Nace | Ethyl Alcohol | Distilled Water | Copper Sulfate | Mass of empty beaker (g) | 50.29 | 50.29 | 50.29 | Mass of beaker and liquid (g) | 94.83 | 99.36 | 100.9 | Mass of liquid (g) | 44.54 | 49.07 | 50.61 | Volume of liquid (mL) | 50 | 50 | 50 | Density of liquid (g/mL) | .891 | .9814 | 1.012 | Accepted value for density (g/mL) | .789 | 1 | 1.3 | Percent error (%) | 12.92 | 1.86 | 22.2 | Data Page: # of copper pieces added | Cumulative mass (g) | Cumulative volume (mL) | 5 | 10.01 | 1 | 5 | 20 | 2 | 4 | 29.95 | 3.5 | 6 | 40.02 | 4.5 | 4 | 50.11 | 5.5 | | 8 Gauge | 18 Gauge | Length of wire (cm) | 15.2 | 27.2 | Mass of wire (g) | 10.68 | 2.01 | Calculated diameter (cm) | .2 | .1 | Accepted value for diameter (cm) | .3 | .1024 | Percent error (%) | 33 | 2.344 | Calculations: Density = Mass/Volume Percent Error = ( IT-EI / T ) x 100 Mass of liquid = mass of liquid and beaker – the mass of the beaker r = Square root [(V)/(PI x h)] Analysis: Our results from this lab show that the densities we found were indeed very close to the accepted values for certain liquids. The results may vary a little bit due to rounding errors or human mistakes. We also saw that as you add ten grams of copper the volume increases by 1mL. Liquids: See data tables for questions 1 through 3 in the liquids section. Copper: 1.