Would the change in enthalpy (ΔH) for the dissolution of urea in water be positive or negative?Homemade...
Can a Bard use the Spell Glyph option of the Glyph of Warding spell and cast a known spell into the glyph?
Older movie/show about humans on derelict alien warship which refuels by passing through a star
What *exactly* is electrical current, voltage, and resistance?
How to not starve gigantic beasts
"Whatever a Russian does, they end up making the Kalashnikov gun"? Are there any similar proverbs in English?
Contradiction proof for inequality of P and NP?
What does MLD stand for?
Is there a word for the censored part of a video?
How much of a wave function must reside inside event horizon for it to be consumed by the black hole?
A strange hotel
Find a stone which is not the lightest one
What to do with someone that cheated their way through university and a PhD program?
How exactly does Hawking radiation decrease the mass of black holes?
As an international instructor, should I openly talk about my accent?
What does a straight horizontal line above a few notes, after a changed tempo mean?
Do I need to watch Ant-Man and the Wasp and Captain Marvel before watching Avengers: Endgame?
Work requires me to come in early to start computer but wont let me clock in to get paid for it
Multiple fireplaces in an apartment building?
Should the Product Owner dictate what info the UI needs to display?
What is the term for a person whose job is to place products on shelves in stores?
Unknown code in script
How to pronounce 'c++' in Spanish
Is there really no use for MD5 anymore?
Retract an already submitted recommendation letter (written for an undergrad student)
Would the change in enthalpy (ΔH) for the dissolution of urea in water be positive or negative?
Homemade reactor for water coolingDifference between internal energy of combustion and enthalpy of combustion?Heat given off from an electrochemical cell compared to mixing reactantsHow can enthalpy change of a system be negative while entropy change is positive?Does exothermic solvation mean solute is more soluble at low temp?What would be the enthalpy change for a isothermal expansion?Why change in enthalpy is negative?Is the crystallization process of aqueous solutions of substances such as lithium chloride endothermic?Why is change in entropy negative and change in enthalpy negative for the reaction of Magnesium and Hydrochloric acid?Does enthalpy of dissolution change with temperature?
$begingroup$
To test the properties of a fertilizer, 15.0 g of urea, NH2CONH2(s), is dissolved in 150mL of water in a simple calorimeter. A temperature change from 20.6 C to 17.8 C is measured. Calculate the molar enthalpy of solution for the fertilizer urea
I worked through this question by finding Q = mcΔT, and then dividing Q by the moles of urea present. I can tell the process is endothermic because ΔT is negative, however my answer for ΔH comes out as negative, which would only make sense if this was an exothermic reaction. I'm not sure where I am wrong to be honest.
Here is my work:
ΔH = (150 mL × 1g/mL × 4.18 J/gC × -2.8 C) ÷ (15 g ÷ 60.07 g) = -7030.59 J/mol, = -7.03 kJ/mol
TL;DR - question asks for ΔH of an endothermic process, not sure if my answer should be positive or negative
thermodynamics water aqueous-solution enthalpy
asked 4 hours ago
ZedEmZedEm
134
New contributor
ZedEm is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
To test the properties of a fertilizer, 15.0 g of urea, NH2CONH2(s), is dissolved in 150mL of water in a simple calorimeter. A temperature change from 20.6 C to 17.8 C is measured. Calculate the molar enthalpy of solution for the fertilizer urea
I worked through this question by finding Q = mcΔT, and then dividing Q by the moles of urea present. I can tell the process is endothermic because ΔT is negative, however my answer for ΔH comes out as negative, which would only make sense if this was an exothermic reaction. I'm not sure where I am wrong to be honest.
Here is my work:
ΔH = (150 mL × 1g/mL × 4.18 J/gC × -2.8 C) ÷ (15 g ÷ 60.07 g) = -7030.59 J/mol, = -7.03 kJ/mol
TL;DR - question asks for ΔH of an endothermic process, not sure if my answer should be positive or negative
thermodynamics water aqueous-solution enthalpy
asked 4 hours ago
ZedEmZedEm
134
New contributor
ZedEm is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
To test the properties of a fertilizer, 15.0 g of urea, NH2CONH2(s), is dissolved in 150mL of water in a simple calorimeter. A temperature change from 20.6 C to 17.8 C is measured. Calculate the molar enthalpy of solution for the fertilizer urea
I worked through this question by finding Q = mcΔT, and then dividing Q by the moles of urea present. I can tell the process is endothermic because ΔT is negative, however my answer for ΔH comes out as negative, which would only make sense if this was an exothermic reaction. I'm not sure where I am wrong to be honest.
Here is my work:
ΔH = (150 mL × 1g/mL × 4.18 J/gC × -2.8 C) ÷ (15 g ÷ 60.07 g) = -7030.59 J/mol, = -7.03 kJ/mol
TL;DR - question asks for ΔH of an endothermic process, not sure if my answer should be positive or negative
thermodynamics water aqueous-solution enthalpy
asked 4 hours ago
ZedEmZedEm
134
New contributor
ZedEm is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
To test the properties of a fertilizer, 15.0 g of urea, NH2CONH2(s), is dissolved in 150mL of water in a simple calorimeter. A temperature change from 20.6 C to 17.8 C is measured. Calculate the molar enthalpy of solution for the fertilizer urea
I worked through this question by finding Q = mcΔT, and then dividing Q by the moles of urea present. I can tell the process is endothermic because ΔT is negative, however my answer for ΔH comes out as negative, which would only make sense if this was an exothermic reaction. I'm not sure where I am wrong to be honest.
Here is my work:
ΔH = (150 mL × 1g/mL × 4.18 J/gC × -2.8 C) ÷ (15 g ÷ 60.07 g) = -7030.59 J/mol, = -7.03 kJ/mol
TL;DR - question asks for ΔH of an endothermic process, not sure if my answer should be positive or negative
thermodynamics water aqueous-solution enthalpy
thermodynamics water aqueous-solution enthalpy
asked 4 hours ago
ZedEmZedEm
134
New contributor
ZedEm is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 4 hours ago
ZedEmZedEm
134
New contributor
ZedEm is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 4 hours ago
ZedEmZedEm
134
New contributor
ZedEm is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 4 hours ago
ZedEmZedEm
134
asked 4 hours ago
ZedEmZedEm
134
134
New contributor
ZedEm is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
ZedEm is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
ZedEm is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
The sign of Q depends on the perspective. The water temperature decreased because it "lost" heat. The process of dissolving urea required energy, it "gained" energy. If I give you a penny, should that be +1 or -1 penny? Well, it depends who you ask.
In your answer, you are missing a negative sign in $Delta H=−Q$ the way you start out with $Q$ from the perspective of the water.
answered 3 hours ago
Karsten TheisKarsten Theis
4,964543
$endgroup$
add a comment |
Your Answer
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "431"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
ZedEm is a new contributor. Be nice, and check out our Code of Conduct.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fchemistry.stackexchange.com%2fquestions%2f114339%2fwould-the-change-in-enthalpy-%25ce%2594h-for-the-dissolution-of-urea-in-water-be-positi%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
The sign of Q depends on the perspective. The water temperature decreased because it "lost" heat. The process of dissolving urea required energy, it "gained" energy. If I give you a penny, should that be +1 or -1 penny? Well, it depends who you ask.
In your answer, you are missing a negative sign in $Delta H=−Q$ the way you start out with $Q$ from the perspective of the water.
answered 3 hours ago
Karsten TheisKarsten Theis
4,964543
$endgroup$
add a comment |
$begingroup$
The sign of Q depends on the perspective. The water temperature decreased because it "lost" heat. The process of dissolving urea required energy, it "gained" energy. If I give you a penny, should that be +1 or -1 penny? Well, it depends who you ask.
In your answer, you are missing a negative sign in $Delta H=−Q$ the way you start out with $Q$ from the perspective of the water.
answered 3 hours ago
Karsten TheisKarsten Theis
4,964543
$endgroup$
add a comment |
$begingroup$
The sign of Q depends on the perspective. The water temperature decreased because it "lost" heat. The process of dissolving urea required energy, it "gained" energy. If I give you a penny, should that be +1 or -1 penny? Well, it depends who you ask.
In your answer, you are missing a negative sign in $Delta H=−Q$ the way you start out with $Q$ from the perspective of the water.
answered 3 hours ago
Karsten TheisKarsten Theis
4,964543
$endgroup$
The sign of Q depends on the perspective. The water temperature decreased because it "lost" heat. The process of dissolving urea required energy, it "gained" energy. If I give you a penny, should that be +1 or -1 penny? Well, it depends who you ask.
In your answer, you are missing a negative sign in $Delta H=−Q$ the way you start out with $Q$ from the perspective of the water.
answered 3 hours ago
Karsten TheisKarsten Theis
4,964543
answered 3 hours ago
Karsten TheisKarsten Theis
4,964543
answered 3 hours ago
Karsten TheisKarsten Theis
4,964543
answered 3 hours ago
Karsten TheisKarsten Theis
4,964543
4,964543
add a comment |
add a comment |
ZedEm is a new contributor. Be nice, and check out our Code of Conduct.
ZedEm is a new contributor. Be nice, and check out our Code of Conduct.
ZedEm is a new contributor. Be nice, and check out our Code of Conduct.
ZedEm is a new contributor. Be nice, and check out our Code of Conduct.
Thanks for contributing an answer to Chemistry Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fchemistry.stackexchange.com%2fquestions%2f114339%2fwould-the-change-in-enthalpy-%25ce%2594h-for-the-dissolution-of-urea-in-water-be-positi%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
