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Oliga [24]
3 years ago
15

A solution is prepared by dissolving 15.0 g of nh3 in 250.0 g of water. the density of the resulting solution is 0.974 g/ml. the

molality of nh3 in the solution is
Chemistry
1 answer:
sergeinik [125]3 years ago
6 0
The formula for molality---> m = moles solute/ Kg of solvent

the solute here is NH₃ because it's the one with less amount. which makes water the solvent.

1) let's convert the grams of NH₃ to moles using the molar mass

molar mass of NH₃= 14.0 + (3 x 1.01)= 17.03 g/ mol

15.0 g (1 mol/ 17.03 g)= 0.881 mol NH₃

2) let's convert the grams of water into kilograms (just divide by 1000)

250.0 g= 0.2500 kg

3) let's plug in the values into the molality formula

molality= mol/ Kg---> 0.881 mol/ 0.2500 kg= 3.52 m
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julsineya [31]
Five valence electrons for one nitrogen and 10 valence electrons for two nitrogens
4 0
3 years ago
2H2 + O2 → 2H2O
pantera1 [17]
Okay
Mr (H2O)= 18g
therefore moles of H2O
is 720.8/18= 40.04mol
the ratio of H2 to O2 to H2O is
2 : 1 : 2
so moles of H2 is same as H2O here
H2= 40.04moles

moles of O2 is half
so 40.04 x 0.5
20.02moles

grams of O2 is
its moles into Mr of O2
that's 20.02 x 32 = 640.64g

6 0
3 years ago
A piece of unknown metal with mass 68.6 g is heated to an initial temperature of 100 °C and dropped into 42 g of water (with an
kogti [31]

The piece of unknown metal is in thermal equilibrium with water such that Q of metal is equal to Q of the water. We write this equality as follows:

-Qm = Qw

Mass of metal (Cm)(ΔT) = Mass of water (Cw) (ΔT)

where C is the specific heat capacities of the materials.

We calculate as follows:

-(Mass of metal (Cm)(ΔT)) = Mass of water (Cw) (ΔT)

-68.6 (Cm)(52.1 - 100) = 42 (4.184) (52.1 - 20)

Cm = 1.717 -----> OPTION C

8 0
3 years ago
Hat is the oxidation state of each element in the compound CaSO4? Include + or - in your answers as appropriate.
quester [9]
As per the rule, oxidation number of alkaline earth metals in their compounds is +2. Oxidation number of oxygen in it's compounds is -2(except peroxides) and the sum of oxidation numbers of all the elements of a neutral compound is zero.
7 0
2 years ago
A sample of magnesium is burned in oxygen to form magnesium oxide. What mass of oxygen is consumed if 74.62 g magnesium oxide is
lana [24]
74.62 g of magnesium oxide is formed from 45.00 g magnesium so 74.62-45.00= 29.62 g of oxygen is consumed or in other words a new compound is formed in the burning of magnesium in oxygen with a heavier mass than the pure magnesium.
3 0
2 years ago
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