True or false An organism needs two dominant alleles to express that trait.

What is the freezing point of a solution of 0.5 mol of LiBr in 500 mL of water? (Kf = 1.86°C/m) –1.86°C –7.44°C –5.58°C –3.72°C

tresset_1 [31]

Answer:

Last choice: - 3.72°C

Explanation:

The freezing point depression in a solvent is a colligative property: it depends on the number of solute particles.

The equation to predict the freezing point depression in a solvent is:

ΔTf = Kf × m × i

Where,

ΔTf is the freezing point depression of the solvent,

m is the molality,

Kf is the cryoscopic molal constant of the solvent, and i is the Van'f Hoff factor, which is the number of ions produced by each unit formula of the ionic compound.

The calcualtions are in the attached pdf file. Please, open it by clicking on the image of the file.

Download pdf

6 0

3 years ago

Find the empirical formula of a compound containing: 19.32% Ca, 34.30% Cl, and 46.38% O

Bess [88]

40×19.32/100=7.7=8×2=16Ca
35.5×34.30/100=12.1=12×2=24Cl
16×46.38/100=7.4=7×2=14O

5 0

3 years ago

You mix 200. mL of 0.400M HCl with 200. mL of 0.400M NaOH in a coffee cup calorimeter. The temperature of the solution goes from

GuDViN [60]

Answer : The enthalpy of neutralization is, 56.012 kJ/mole

Explanation :

First we have to calculate the moles of HCl and NaOH.

$\text{Moles of HCl}=\text{Concentration of HCl}\times \text{Volume of solution}=0.400mole/L\times 0.200L=0.08mol$

$\text{Moles of NaOH}=\text{Concentration of NaOH}\times \text{Volume of solution}=0.400mole/L\times 0.200L=0.08mol$

The balanced chemical reaction will be,

$HCl+NaOH\rightarrow NaCl+H_2O$

From the balanced reaction we conclude that,

As, 1 mole of HCl neutralizes by 1 mole of NaOH

So, 0.08 mole of HCl neutralizes by 0.08 mole of NaOH

Thus, the number of neutralized moles = 0.08 mole

Now we have to calculate the mass of water.

As we know that the density of water is 1 g/ml. So, the mass of water will be:

The volume of water = $200mL+200L=400mL$

$\text{Mass of water}=\text{Density of water}\times \text{Volume of water}=1g/ml\times 400mL=400g$

Now we have to calculate the heat absorbed during the reaction.

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

where,

q = heat absorbed = ?

$c$ = specific heat of water = $4.18J/g^oC$

m = mass of water = 400 g

$T_{final}$ = final temperature of water = $27.78^oC=273+25.10=300.78K$

$T_{initial}$ = initial temperature of metal = $25.10^oC=273+27.78=298.1K$

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

$q=400g\times 4.18J/g^oC\times (300.78-298.1)K$

$q=4480.96J$

Thus, the heat released during the neutralization = -4480.96 J

Now we have to calculate the enthalpy of neutralization.

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

where,

$\Delta H$ = enthalpy of neutralization = ?

q = heat released = -4480.96 J

n = number of moles used in neutralization = 0.08 mole

$\Delta H=\frac{-4480.96J}{0.08mole}=-56012J/mole=-56.012kJ/mol$

The negative sign indicate the heat released during the reaction.

Therefore, the enthalpy of neutralization is, 56.012 kJ/mole

8 0

3 years ago

Give the name for the strongest intermolecular interaction between the substrate and the following amino acids on the star prote

mel-nik [20]

Answer:

The answer is IONIC BOND

Explanation:

Steroidogenic acute regulatory, (StAR) protein is a type of globular protein, which allows it act as an active catalyst on substrates. Because the substrates on which enzymes act usually have higher molecular weights of several hundred as compared to the enzymes, only a fraction of the enzyme's surface is in contact with the substrate. This region of contact called the active site, is as a result of the protein folding itself into a tertiary structure.

Once the correct substrate has bound at the active site of the enzyme, an enzyme-substrate complex is created. The substrate is usually held in the complex by combinations of electrical attraction, hydrophobic repulsion, or hydrogen bonding between and from the amino acid; the strongest of which is the ionic/electrostatic bonding due to larger amount of ionic "R" groups in the protein structure.

So whilst all these inter-molecular interactions are possible, the strongest would be ionic bond.

4 0

3 years ago

How many electrons does carbon need to gain to obtain a noble gas electron configuration

laila [671]

Carbon has 4 valence electrons so to gain a noble gas electron configuration, which has 8 valence electrons and is the most electrically stable, carbon needs 4 more electrons.

4 0

3 years ago