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March 29, 2024, 07:39:04 am

Author Topic: VCE Chemistry Question Thread  (Read 2313384 times)  Share 

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Acegtr

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Re: VCE Chemistry Question Thread
« Reply #9225 on: November 09, 2021, 06:08:54 pm »
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Hey guys,
I'm currently doing chem 1/2 in yr11, and I want to start prepping for chem 3/4 soon, and was just wondering how heavily does 3/4 involve experimental design?
I haven't encountered it too much in 1/2 (only did a few pracs this yr cuz of lockdowns), but wanted to know if it's anything like Biology 3/4, where they spam experimental design.

Thanks in advance!

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Re: VCE Chemistry Question Thread
« Reply #9226 on: November 10, 2021, 09:22:28 pm »
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Hi,

Was just wondering if this is a mistake in the textbook, or not (since in Physics I am pretty sure the unit for mass is kilograms not grams)


Thanks.

caffinatedloz

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Re: VCE Chemistry Question Thread
« Reply #9227 on: November 10, 2021, 10:14:19 pm »
+2
Hi,

Was just wondering if this is a mistake in the textbook, or not (since in Physics I am pretty sure the unit for mass is kilograms not grams)


Thanks.

Mass for chem is often in grams but I think you're right. It should be kilograms. I think that is a mistake in the textbook.

WhatisaMeMe

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Re: VCE Chemistry Question Thread
« Reply #9228 on: November 10, 2021, 10:58:25 pm »
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Hi,

Was just wondering if this is a mistake in the textbook, or not (since in Physics I am pretty sure the unit for mass is kilograms not grams)


Thanks.
dont worry about that lmao literally never used it ever
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TnGn74

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Re: VCE Chemistry Question Thread
« Reply #9229 on: November 15, 2021, 09:13:17 pm »
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Hi, a few questions about significant figures requirements.
My teacher said that temperature should not be considered when determining the significant figures, essentially to assume that given temperatures are perfectly exact and implicitly have infinite significant figures. Can anybody confirm this?
Also, what are the significant figures guidelines for logarithms and exponents of base 10?
Thanks.

miyukiaura

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Re: VCE Chemistry Question Thread
« Reply #9230 on: November 15, 2021, 09:24:36 pm »
+1
Always include temperature because it is often given as part of an experiment (e.g. the temperature was measured using a thermometer which has uncertainty)

I don't think VCE chemistry deals with logs and exponents for significant figures
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Rose34

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Re: VCE Chemistry Question Thread
« Reply #9231 on: November 19, 2021, 07:35:49 am »
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Hey guys!

Does anyone know why the presence of oxygen in biodiesel prevents carbon atoms from being fully oxidised? And why is oxidation harmful to the environmnet?

Thanks in advance.

UrekMazino

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Re: VCE Chemistry Question Thread
« Reply #9232 on: November 19, 2021, 09:13:41 am »
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Hi, a few questions about significant figures requirements.
My teacher said that temperature should not be considered when determining the significant figures, essentially to assume that given temperatures are perfectly exact and implicitly have infinite significant figures. Can anybody confirm this?
Also, what are the significant figures guidelines for logarithms and exponents of base 10?
Thanks.

Hi,
I'm doing Year 11 WACE Chemistry, so it might be slightly different to the VCE requirements, but my teacher always says to use four decimal places in calculations and the final answer (if it, when put in scientific notation, is at least 10^3 or 10^-3) be to three significant figures in scientific notation.

Temperature seems to be to two decimal places, and our pH calculations are also two decimal places (assuming that's what you mean when asking about log calculations).

Yeah, so in general four decimal places for smaller numbers in calculations (for accuracy's sake), two for pH and temp, and three significant figures for exponents or numbers that can be turned into exponents to at least the positive or negative third power.

keltingmeith

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Re: VCE Chemistry Question Thread
« Reply #9233 on: November 23, 2021, 08:20:11 pm »
+2
Hi,
I'm doing Year 11 WACE Chemistry, so it might be slightly different to the VCE requirements, but my teacher always says to use four decimal places in calculations and the final answer (if it, when put in scientific notation, is at least 10^3 or 10^-3) be to three significant figures in scientific notation.

Temperature seems to be to two decimal places, and our pH calculations are also two decimal places (assuming that's what you mean when asking about log calculations).

Yeah, so in general four decimal places for smaller numbers in calculations (for accuracy's sake), two for pH and temp, and three significant figures for exponents or numbers that can be turned into exponents to at least the positive or negative third power.

VCE is very different to this - but also, the rules I know from WACE are very different to what you're describing. Might want to double check your textbook, and then confirm with your teacher?

Hey guys!

Does anyone know why the presence of oxygen in biodiesel prevents carbon atoms from being fully oxidised? And why is oxidation harmful to the environmnet?

Thanks in advance.

First I've heard of that lol, where did you get that piece of information from?

Oxidation isn't necessarily bad for the environment. Is there a question you've been asked that suggests it is? There might be something else in the context of the question that you're missing

Chocolatepistachio

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Re: VCE Chemistry Question Thread
« Reply #9234 on: December 10, 2021, 10:00:11 pm »
0
does a higher wavelength increase absorbance

Billuminati

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Re: VCE Chemistry Question Thread
« Reply #9235 on: December 10, 2021, 11:33:26 pm »
+2
does a higher wavelength increase absorbance

It depends where the absorption maximum/maxima is/are for your particular chromophore. The absorbance which is directly proportional to the molar extinction coefficient will be lower on either side of this turning point (remember you have wavelength on your x-axis and absorbance on your y-axis). The specific nature of the λmax is due to a combination of electronic and vibrational energy level transitions in your molecule
« Last Edit: December 10, 2021, 11:37:51 pm by Billuminati »
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galaxysauce

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Re: VCE Chemistry Question Thread
« Reply #9236 on: January 07, 2022, 04:47:51 pm »
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Hi! Can someone please help me with part b? Thank you!

Billuminati

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Re: VCE Chemistry Question Thread
« Reply #9237 on: January 07, 2022, 04:54:37 pm »
+2
Hi! Can someone please help me with part b? Thank you!
(Image removed from quote.)

By dimensional analysis (unit cancelling), 1250 J K-1 x 1.78 K = 2225 J (report as 2230 J or 2.23 kJ as least number of sig figs is 3). Note that it's not scientifically accurate to use °C as part of the unit even though the increments of the Celsius scale are equivalent to the Kelvin scale. This is because only K is the SI unit for temperature as it's an absolute scale.
« Last Edit: January 07, 2022, 05:06:37 pm by Billuminati »
VCE 2016-2018

2017: Biology [38], Further Maths [44]

2018: Methods [37], French [38], Chem [40], English [44]

UMAT: 56/43/80, 57th percentile (LLLLOOOOOOOOOLLLLLLLL)

ATAR: 98.1

2019-2021: Bachelor of Biomedical Science at Monash (Scholars), minoring in Chemistry

GAMSAT September 2021: 65/67/86, 76 overall (98th percentile)

2022: Chilling

2023+: Transfer to teaching degree

ArtyDreams

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Re: VCE Chemistry Question Thread
« Reply #9238 on: January 07, 2022, 07:50:35 pm »
+3
Hi! Can someone please help me with part b? Thank you!
(Image removed from quote.)

In addition to billuminati's great answer, you can also use (it is worth while to remember it/note it down) the formula for the calibration factor.

CF = energy used/temperature change
You can rearrange as needed to find the energy used.

This formula is in your data book :)

Don't forget to use the appropriate units as billuminati has shown above.
« Last Edit: January 07, 2022, 07:52:27 pm by ArtyDreams »

Rose34

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Re: VCE Chemistry Question Thread
« Reply #9239 on: January 08, 2022, 05:49:27 pm »
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Can someone explain why the anode is positive and the cathode is negative in electrolytic cells?

Thanks in advance!