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2 years ago

2. Imagine you have just baked a pizza in the oven. You've only let it cool for a minute, but you're

Chemistry

1 answer:

GaryK [48]2 years ago

3 0

Answer:

You should take a bite near the crust that contains very little sauce.

Explanation:

Specific heat capacity is amount of heat a one gram of substance must absorb or lose to change its temperature by one degree Celsius.

The sauce has water in it. Water has a high high heat capacity,( i.e 4.186 J/g °C, ) which means that the sauce takes more time to cool, as a result the sauce is still be hot even after few minutes of cooling, as compared to crust which has less sauce so it will cool faster.

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An amount of solid barium chloride, 20.8 g, is dissolved in 100 g water in a coffee-cup calorimeter by the reaction: BaCl2 (s) 

mamaluj [8]

Answer : The enthalpy change during the reaction is -6.48 kJ/mole

Explanation :

First we have to calculate the heat gained by the reaction.

$q=m\times c\times (T_{final}-T_{initial})$

where,

q = heat gained = ?

m = mass of water = 100 g

c = specific heat = $4.04J/g^oC$

$T_{final}$ = final temperature = $26.6^oC$

$T_{initial}$ = initial temperature = $25.0^oC$

Now put all the given values in the above formula, we get:

$q=100g\times 4.04J/g^oC\times (26.6-25.0)^oC$

$q=646.4J$

Now we have to calculate the enthalpy change during the reaction.

$\Delta H=-\frac{q}{n}$

where,

$\Delta H$ = enthalpy change = ?

q = heat gained = 23.4 kJ

n = number of moles barium chloride = $\frac{\text{Mass of barium chloride}}{\text{Molar mass of barium chloride}}=\frac{20.8g}{208.23g/mol}=0.0998mole$

$\Delta H=-\frac{646.4J}{0.0998mole}=-6476.95J/mole=-6.48kJ/mole$

Therefore, the enthalpy change during the reaction is -6.48 kJ/mole

8 0

2 years ago

Be sure to answer all parts. Draw the structure of a compound of molecular formula C4H8O that has a signal in its 13C NMR spectr

GenaCL600 [577]

Answer:

The possible structures are ketone and aldehyde.

Explanation:

Number of double bonds of the given compound is calculated using the below formula.

$N_{db}=N_{c}+1-\frac{N_{H}+N_{Br}-N_{N}}{2}$

$N_{db}$ =Number of double bonds

$N_{c}$ = Number of carbon atoms

$N_{H}$ = Number of hydrogen atoms

$N_{N}$ = Number of nitrogen atoms

The number of double bonds in the given formula - $C_{4}H_{8}O$

$N_{db}= 4+1-\frac{8+0-0}{2}=1$

The number of double bonds in the compound is one.

Therefore, probable structures is as follows.

(In attachment)

The structures I and III are ruled out from the probable structures because the signal in 13C-NMR appears at greater than 160 ppm.

alkene compounds I and II shows signal less than 140 ppm.

Hence, the probable structures III and IV are given as follows.

The carbonyl of structure I appear at 202 and ketone group of IV appears at 208 in 13C, which are greater than 160.

Hence, the molecular formula of the compound $C_{4}H_{8}O$ having possible structure in which the signal appears at greater than 160 ppm are shown aw follows.

8 0

2 years ago

A mixture of three noble gases has a total pressure of 1.25 atm. The individual pressures exerted by neon and argon are 0.68 atm

vlabodo [156]

Add the Pressure of neon and argon that is 0.68 +0.35= 1.03
Total pressure that is 1.25 -1.03=0.22 atm

5 0

2 years ago

Read 2 more answers

Enter the balanced complete ionic equation for k2so4(aq)+cai2(aq)→caso4(s)+ki(aq). express your answer as a chemical equation. i

frozen [14]

The ionic equation is as below

Ca^2+(aq) + SO4^2-(aq) ---> CaSO4(s)

EXPLANATION

K2SO4(aq) +Cai2(aq) ---> CaSO4(s) + Ki (aq)

ionic equation

= 2K^+(aq) + SO4^2-(aq) + Ca^2+(aq) + 2i^-(aq) --->CaSO4(s) + 2K^+(aq) +2 i^-(aq)

cancel the spectator ions that is 2k^+ and 2i^-

The net ionic equation is therefore

= Ca^2+(aq) + SO4^2-(aq) ----> CaSO4(s)

6 0

2 years ago

Read 2 more answers

The combustion of one mole of liquid ethanol, CH3CH2OH, produces 1367 kJ of heat. Calculate how much heat is produced when 235.0

deff fn [24]

Answer:- 6984 kJ of heat is produced.

Solution:- From given information, 1367 kJ of heat is produced by the combustion of 1 mole of ethanol. We are asked to calculate the heat produced by the combustion of 235.0 g of ethanol.

Let's convert given grams to moles and multiply by the heat produced by one mole of ethanol to get the total heat produced. Molar mass of ethanol is 46 grams per mole. The set will be:

$235.0g(\frac{1mole}{46g})(\frac{1367 kJ}{1mole})$

= 6984 kJ

So, 6984 kJ of heat is produced by the combustion of 235.0 g of liquid ethanol.

6 0

2 years ago