Around how much do hot plate heat knobs increase per number?

Click For Summary

Discussion Overview

The discussion revolves around the temperature settings of hot plates with a 0-10 knob scale, specifically how much heat each increment corresponds to in practical laboratory settings. Participants explore the variability of temperature readings based on different factors such as the type and amount of substance being heated, as well as the influence of environmental conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that the hot plates range from 25°C at setting "1" to 550°C at setting "10", but questions the accuracy of these readings based on what is placed on the plate.
  • Another participant emphasizes that the temperature will vary depending on the size of the container used, suggesting that larger containers dissipate heat more effectively, resulting in lower temperatures.
  • Some participants express uncertainty about whether the 25°C reading refers to the plate itself or a specific substance, indicating a lack of clarity in the manufacturer's information.
  • It is mentioned that the only reliable way to know the actual temperature is to use a thermometer, as the knob settings represent power levels rather than direct temperature readings.
  • A participant suggests that the scale may be logarithmic rather than linear, implying that increments on the knob do not correspond to equal temperature increases.

Areas of Agreement / Disagreement

Participants generally agree that the temperature readings are not straightforward and depend on various factors, but there is no consensus on the specifics of how the knob settings translate to actual temperatures or the nature of the scale.

Contextual Notes

Limitations include the dependence on the type and amount of substance being heated, as well as environmental conditions that may affect heat transfer. The discussion highlights the variability and uncertainty in using hot plates without precise temperature monitoring.

AMan24
Messages
58
Reaction score
2
In my labs we use hot plates with a 0-10 temperature knob. The hot plates don't have a temperature monitor, so i have no idea how hot each number can increase it or how hot it is at the time. Sometimes i have labs where i have to heat something to more specific temperatures or else the reaction will change or it will boil over. My only option right now is to use a thermometer which isn't always practical, and still its easy to mess up.

Is there a general rule with hot plates and the heat knob numbers? I know there might be factors like, room temperature. But I'm not doing anything that requires super precision, so i only really need a decent estimate. The only thing i know is the temperatures are 25°C at "1" and 550°C at "10"

We use these http://www.sigmaaldrich.com/catalog/product/aldrich/cls6795220?lang=en&region=US

Only thing i could think of is heating water and checking the temperature before heating anything important. But i won't have enough time for that. And my professor might say things like "watch it and don't let it boil too violently", but i just feel like there's just too much of a chance of messing up.
 
Last edited:
Chemistry news on Phys.org
AMan24 said:
The only thing i know is the temperatures are 25°C at "1" and 550°C at "10"
.

The temperature of what is 25c at 1 ? ... the temperature of the plate with nothing on it? ...or a small beaker of water ...or a large beaker of water?

The temperature will vary depending what you have on the plate ... a big beaker of water will have a lower temperature because it has a larger surface area and dissipates the heat to the environment more effectively , a small beaker of water will get hotter , for a given setting.
 
  • Like
Likes   Reactions: AMan24
oz93666 said:
The temperature of what is 25c at 1 ? ... the temperature of the plate with nothing on it? ...or a small beaker of water ...or a large beaker of water?

The temperature will vary depending what you have on the plate ... a big beaker of water will have a lower temperature because it has a larger surface area and dissipates the heat to the environment more effectively , a small beaker of water will get hotter , for a given setting.

I'm not sure, i got it from the website. I'm assuming its the plate but i have no idea. And yeah the temperature would be different depending on the amount of what I am heating, but I'm asking this for smaller amount substances, i should have specified that.
 
AMan24 said:
I'm not sure, i got it from the website. I'm assuming its the plate but i have no idea

I see that now from the website "25-550 °C temp. range" ...I would imagine 25c (room temp) is setting zero ... there's no way you can know the temp...every item you put on the plate has different heat transfer properties , only through experience ... as the prof says "watch it"
 
  • Like
Likes   Reactions: AMan24
AMan24 said:
I'm not sure, i got it from the website. I'm assuming its the plate but i have no idea. And yeah the temperature would be different depending on the amount of what I am heating, but I'm asking this for smaller amount substances, i should have specified that.

The only way of being sure is to use a thermometer so no maker will give other scale than the power on the plate (which is what these 0..10 marks on the knob really are).

When you are working in a repeatable settings (air-conditioned room with a constant temperature, always the same sample/vessel size) you can prepare your own table of what settings to use. Even then occasionally checking if the temperature is what you think it is won't hurt.
 
  • Like
Likes   Reactions: AMan24
You really just need to know your hotplate. IIRC, the scale is logarithmic, not linear.
 

Similar threads

Simple distillation of compounds with similar boiling points
  • · Replies 8 ·
Replies
8
Views
7K
Heat transfer in wing by anti-ice system using hot air in piccolo tube
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad Is low entropy found in something very hot?
  • · Replies 26 ·
Replies
26
Views
3K
High School Too much energy -- thought experiment
  • · Replies 42 ·
2
Replies
42
Views
5K
High School Power of a hot plate and actual heat power delivered
  • · Replies 3 ·
Replies
3
Views
4K
Need advice and hints for working with helium
  • · Replies 14 ·
Replies
14
Views
1K
As much steam as possible from engine exhaust gas + warm water?
  • · Replies 25 ·
Replies
25
Views
4K
Misc. How can I calculate the necessary heating power for a 3D printer chamber?
  • · Replies 2 ·
Replies
2
Views
3K
Help me heat up a powder coating oven (made out of an old steel cabinet)
  • · Replies 9 ·
Replies
9
Views
2K
Heat required to increase the temperature
  • · Replies 4 ·
Replies
4
Views
2K