Which of these is a base?

How many grams of water at 50◦c must be added to 16 grams of ice at −12◦c to result in only liquid water at 0◦c?

melisa1 [442]

When water at 50 C is added to ice at -12 C, heat is transferred from hot water to ice.

- Heat given out by water = Heat absorbed by ice

Calculating the heat released by hot water:

$q = m Cwater$ ΔT $q = m (4.184\frac{J}{(g.^{0}C)} )$ $(0^{0}C-50^{0}C)$

Calculating heat absorbed by 16 g of ice: Ice at $-12^{0}C$ is converted to ice at $O^{0}C$ and then ice at $O^{0} C$ to water at $0^{0}C$

$q = m Cice$ ΔT + $m (Heat of fusion)$

$q = 16 g(2.11\frac{J}{g.^{0}C})(0^{0}C - (-12^{0}C))$ + $16 g (333.55\frac{J}{g})$

q = 405.12 J +5336.8 J =5741.92 J

- Heat given out by water = Heat absorbed by ice

-( $m(4.184\frac{J}{g.^{0}C})(0^{0}C-50^{0}C) = 5741.92 J$

m = 27.4 g

Therefore, 27.4 g water at $50^{0}C$ must be added to 16 g of ice at $-12^{0}C$ to convert to liquid water at $0^{0}C$

4 0

3 years ago

draw the lewis structure for CO2, H2CO3, HCO3-, and CO3 2-.Rank these in order of increasing attraction to water molecules. Expl

gavmur [86]

Answer:

The structures are attached in file.

Hydrogen bonding and intermolecular forces is the reason for ranks allotted.

Explanation:

In determining Lewis structure, we calculate the overall number of valence electrons available for bonding. Making carbon (the least electronegative atom) the central atom in the structure, we allocate valence electrons until each atom has achieved stability.

In order of decreasing affinity to water molecules:

$CO_{3}^{2-} > HCO_{3} ^{2-} > H_{2} CO_{3}$

This is due to the fact that the $CO_{3}^{2-}$ will accept protons more readily than the bicarbonate ion, $HCO_{3} ^{2-}$ . Carbonic acid, $H_{2} CO_{3}$ will not accept any more protons, hence it is the least attractive to water molecule, even though soluble.

3 0

3 years ago

Using your knowledge of reagents that react with alkenes, what would be a reagent that you could use to check and see if the hyd

igomit [66]

Answer:

An halogen addition reaction, particularly bromine addition, could be used to check if the hydrogenation has completed.

Explanation:

The aim is to find a way to check if the hydrogenation process of an alkene has completed. So the logic should be use a reaction that needs the participation of the double bound of the alkene, and therefore shouldn't take place in the process has finished.

A simple organic reaction is the halogen addition reaction, which occur between the halogen molecule and the double bond of the alkene. Basically, the pi electrons of the double bond attacks a relatively electrophilic halogen atom following a mechanism that leads to the addition of two halogen atoms to the double bond. As a consequence the alkene transforms into an haloalkane.

Also, a commonly used halogen is bromine, as it has a reasonable reactivity and it has red colour, which allows to monitor the progression of the reaction.

Taking all this in account, we can say that using a bromine addition reaction to the alkene it's a good option to check the completion of the hydrogenation.

Note that the bromine will react only if the double bond is present. So, if the hydrogenation has completed, the reaction won't occur. Using bromine will be the best option, as it is red coloured. That means that is we add bromine to an incomplete hydrogenation, as it will react with the alkene, the colour should disappear.

In other words, to check if the hydrogenation reaction has completed, we should add bromine and see what happens to the colour. If it doesn't change, then the hydrogenation reaction has completed.

3 0

3 years ago

Which of the following groups would be found on an alcohol molecule?

photoshop1234 [79]

I’ve answered this question before so if these are the choices to the question presented:

An oxygen atom double-bonded to a carbon atom, with a hydrogen atom single-bonded to the same carbon atom. 

A hydrogen atom covalently bonded to an oxygen atom, which is covalently bonded to a carbon in the carbon chain. 

A carbon atom single-bonded between two other carbon atoms, with an oxygen atom double-bonded to the central carbon atom as well. 

An oxygen atom single-bonded between two carbon atoms within a carbon chain.

Then, the answer would be “a hydrogen atom covalently bonded to an oxygen atom, which is covalently bonded to a carbon in the carbon chain.”

5 0

2 years ago

3. The formula for table salt is NaCl. Is table salt ionic or covalent? Explain

d1i1m1o1n [39]

Answer:

it's an ionic compound

7 0

3 years ago