Discussion
Explain the relationship
1. Pressure drop and boil-up rate
As seen from graph 2, pressure drop increases as the boil-up rate increases.
The reflux ratio is kept constant so the liquid flowing down has uniform flow and only the power input to the reboiler can be adjusted. The boil-up rate is obtained by varying the heat energy to the reboiler and this affects the velocity of the vapour passing up the column. As the velocity of the vapour passing up the column increases, the vapour flow will generate more pressure drop due to the resistance force that is acting against the holes in the sieve tray and the liquid that is flowing down the column. In addition, increasing the vapour flow means that increasing the contacting time between liquid and vapour phase inside the column resulting in higher pressure drop. This is proven clearly from the graph that the pressure drop is linearly related with boil-up rate.
Therefore, the relationship between pressure drop and boil-up rate means that more volume of vapour educed per unit time results in more restriction of the holes in the sieve tray and that caused by passing of vapour through the liquid on top of the tray. Hence, the higher the velocity, the higher the boil-up rate and so does the overall pressure drop.
2. Purity and boil-up rate
From the graph 2, it is seen clearly that the relationship between purity and boil-up rate is inversely proportional to each other. In order to achieve a good separation and high purity between the liquid and the vapour must be brought to an intimate contact by counter-current flow. Increasing the vapour flow actually means decreasing the interaction time between the down flowing liquid and up flowing vapour inside the column. Hence, if ...
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...mes more violent and spread out.
4. Pressure drop and foaming
As the pressure drop increases in the column, it is observed that the degree of foaming becomes more violent and more spread out. When the pressure drop is relatively high, it means that the pressure exerted by the vapour is insufficient to hold up the liquid in the tray, causing the gas bubbles to appear on top of the sieve trays. To add on, the higher the pressure drop, the higher the velocity of the vapour passing up the column. As a result, more vapour will penetrate the liquid and more bubbles formation is observed. Due to more bubbles formation, the degree of foaming are more agitated, rapid and spread out.
The bubbles forms become more spread out when the pressure drop increases because the pressure acting on the holes of the sieve trays causes to push the bubbles against the other bubbles.
If the solution is stirred more there are more collisions between the particles. therefore the reaction is speeded up). Temperature of Water - °C. As the temperature increases so does the rate of the reaction. By increasing the temperature, particles move.
Theory: Steam distillation uses boiling point to separate organic liquid and water. The organic compound must be immiscible with water, have a high vapor pressure at 100˚C, and may decompose before boiling point is reached. Steam distillation increases the vapor pressure of water more than the vapor pressure of the organic compound as temperature rises to reach the boiling point of the mixture which is a little less than 100 ˚C (boiling point of water) but a lot less than 254 ˚C (boiling point of eugenol). Since the liquids are immiscible, the total vapor pressure only depends on the vapor pressure of each component added together and not the mole fraction leading to a higher vapor pressure which corresponds to the lower boiling point.
The boiling point of a substance is “the temperature at which the total vapor pressure of the liquid is equal to the external pressure” (Gilbert & Martin 2011). Boiling point is the point at which the evaporation rate of a given liquid increases as bubbles are formed. The boiling point is usually determined by “reading the thermometer during a simple distillation” (Gilbert & Martin 2011). However for the purposes of this lab, a miniscale method was used to determine the boiling point. This method requires for a liquid to be heated using the apparatus seen in Figure 1. A thermometer is placed just above the liquid at a height where the thermometer is able to measure the vapor temperature of the liquid, not the liquid itself. As the liquid heats, the temperature rises until it reaches an equilibrium where it cannot increase any
enclosure is driven by the strength of the hydrogen bonds between the water molecules, leading
The more concentration or more volume there is of an acid, the more acid. molecules there are that can react with the chalk. The larger the surface area of a solid, the more surface there is for acid to collide. with and react with. Higher pressure pushes the molecules closer.
The hypothesis for this experiment was, If three different types of waters (saltwater, fresh water, tap water) are tested, then the liquids won’t evaporate at the same rate and tap water will evaporate at the fastest rate because it won’t have any non-volatile substances to hold it back from evaporating.
We can see oxygen bubbles being let through the glass tube into the beaker. This shows the decomposition of H2O2 . Start the stopwatch and also start counting the no. of bubbles produced. 4) Note down the results for every minute, up to 5 minutes. 5)
Process cd : This liquid refrigerant is collected in the liquid storage tank and later on it is expanded to low pressure and temperature by passing it through the throttle valve. At point d we have low temperature liquid refrigerant with small amounts of vapour .
Capillary action can only occur when the adhesive forces are stronger than the cohesive forces, which creates surface tension in liquid. The kinetic energy produced when the liquid is heated, allows the attractive forces between the molecules to weaken and this causes them to move past each other more freely. This results in the liquid flowing more easily. Therefore temperature increases capillary action and capillary flow because of the decrease in cohesive force. The intermolecular forces between the molecules are less packed due to the increase in temperature and the surface tension in the liquid will decrease as the temperature increases and this will help the flow of the liquid through the capillary tube.
Advantage of steam lies in the blatant heat liberated when it condenses on a cooler surface raising the temp of that surfaces.
The effect of Temperature of liquid on flow rate. - the effect of Temperature on liquid flow (turbulent/laminar) 3) The effect of the Vertical height between source and destination of the fluid on flow rate. - the effect of Vertical height on liquid flow (turbulent/laminar) 4) The effect of the Liquid's Viscosity/Density on flow rate.
10. A packed fractionating column is more efficient than an unpacked one because a packed column provides more surface area for the vapor to condense on. The more it condenses, the more efficient the separation of the liquids.
Third, the liquid will enter to the expansion valve with the higher pressure and leaves with the low pressure.