## Units for t

$\frac{d[R]}{dt}=-k[R]; \ln [R]=-kt + \ln [R]_{0}; t_{\frac{1}{2}}=\frac{0.693}{k}$

MaryBanh_2K
Posts: 101
Joined: Wed Sep 18, 2019 12:21 am

### Units for t

What are the correct units for t? The solutions manual leaves it in minutes but aren't the correct units in seconds?

Brian_Ho_2B
Posts: 221
Joined: Fri Aug 09, 2019 12:16 am

### Re: Units for t

Time is generally written as seconds (as the standard SI unit); however, it can be represented as minutes or hours depending on the duration of the reaction. If you do happen to change time from seconds to minutes or from hours to minutes and so on, remember to change the value and units of your "k" value so that the units at the end match up.

Kishan Shah 2G
Posts: 132
Joined: Thu Jul 11, 2019 12:15 am

### Re: Units for t

You can use whichever units you would like but, as Brian said, make sure the units match up in all of your terms before solving.

Luc Zelissen 1K
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Joined: Mon Jun 17, 2019 7:23 am

### Re: Units for t

It easiest if you change the t value to the time value of your rate constant. In this way you can easily multiply and get the right answer without changing the rate constant units.

Anna Heckler 2C
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Joined: Wed Sep 18, 2019 12:18 am

### Re: Units for t

t can be in seconds, minutes, or hours, but MUST be consistent across all terms or it will mess up your calculations.

705302428
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Joined: Sat Aug 24, 2019 12:16 am

### Re: Units for t

I think it depends

Tanmay Singhal 1H
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### Re: Units for t

i think it depends on what the problem asks for. most times in calculations it is seconds

Myka G 1l
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Joined: Fri Aug 30, 2019 12:17 am

### Re: Units for t

T can be in either seconds, minutes, or hours depending on what the problem asks for. As before mentioned the same units must be used throughout the problem.

Rodrigo2J
Posts: 102
Joined: Sat Jul 20, 2019 12:16 am

### Re: Units for t

t can be in any unit of time depending on what is asked in the problem. Seconds is generally used because it is the SI unit we have associated with time. Just make sure that your units cancel and that the math makes sense.

Leonardo Le Merle 1D
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Joined: Wed Feb 27, 2019 12:16 am

### Re: Units for t

Just to ensure I didn't mix up anything I usually convert everything to seconds before trying to solve the problem - if it asks to be expressed in minutes or hours you can convert back at the end.

Ying Yan 1F
Posts: 101
Joined: Fri Aug 02, 2019 12:16 am

### Re: Units for t

It usually just depends on the units of the information you were given in the problem. I'm pretty sure you won't be marked wrong if you leave your t in either minutes or seconds (or even hour) as it is the correct number of sec/min/hr. I hope this helped!

Posts: 50
Joined: Tue Nov 05, 2019 12:18 am

### Re: Units for t

The units of t depend on the problem, but be consistent when doing calculations!

Samuel Tzeng 1B
Posts: 103
Joined: Sat Aug 24, 2019 12:15 am

### Re: Units for t

The SI units for time is seconds

Alfred Barrion 2H
Posts: 100
Joined: Sat Jul 20, 2019 12:16 am

### Re: Units for t

It honestly depends on the context of the question, but I use seconds because it is the SI unit. It also depends on your k.