All categories

3 years ago

All the nonmetals have some similar physical properties. True False

2 answers:

8 0

<span>All the nonmetals have some similar physical properties is false because
</span><span>all non metals within the same group have similar properties.</span>

OLEGan [10]3 years ago

5 0

TRUE.

Nonmetals have some similar physical properties.

En general:

- They are either gases or brittle solids.
- They are opaque
- They are poor conductors of heat and electricity.

You might be interested in

Some velomobile seats have been designed to hold ice packs inside their cushions. If you started a ride with ice packs that held

Cerrena [4.2K]

Answer : The heat energy absorbed will be, $1.23\times 10^5cal$

Solution :

The process involved in this problem are :

$(1):H_2O(s)(0^oC)\rightarrow H_2O(l)(0^oC)\\\\(2):H_2O(l)(0^oC)\rightarrow H_2O(l)(32.0^oC)$

The expression used will be:

$\Delta H=m\times \Delta H_{fusion}+[m\times c_{p,l}\times (T_{final}-T_{initial})]$

where,

m = mass of ice = 1100 g

$c_{p,l}$ = specific heat of liquid water = $4.18J/g^oC$

$\Delta H_{fusion}$ = enthalpy change for fusion = $6.01kJ/mole=6010J/mole=\frac{6010J/mole}{18g/mole}J/g=333.89J/g$

Molar mass of water = 18 g/mole

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

$\Delta H=1100g\times 333.89J/g+[1100g\times 4.18J/g^oC\times (32.0-0)^oC]$

$\Delta H=514415J=122948.1358cal=1.23\times 10^5cal$

Conversion used : (1 cal = 4.184 J)

Therefore, the heat energy absorbed will be, $1.23\times 10^5cal$

7 0

3 years ago

A solution is 40.00% by volume benzene (C6H6) in carbon tetrachloride at 20°C. The vapor pressure of pure benzene at this temper

finlep [7]

Answer:

The total vapor pressure is 84.29 mmHg

Explanation:

Step 1: Data given

Solution = 40.00 (v/v) % benzene in CCl4

Temperature = 20.00 °C

The vapor pressure of pure benzene at 20.00 °C = 74.61 mmHg

Density of benzene is 0.87865 g/cm3

The vapor pressure of pure carbon tetrachloride is 91.32 mmHg

We suppose the total volume = 100 mL

Step 2: Calculate volume benzene and CCl4

40 % benzene = 40 mL

60 % mL CCl4 = 60 mL

Step 3: Calculate mass benzene

Mass = density * volume

Mass of benzene = 40.00 mL * 0.87865 g/mL = 35.146 g

Step 4: Calculate moles of benzene

Moles = mass / molar mass

Number of moles of benzene = 35.146 grams / 78 g/mol = 0.45059 mol

Step 5: Calculate mass of CCl4

Mass of CCl4 = 60 mL * 1.5940 g/mL = 95.64 g

Step 6: Calculate moles CCl4

Number of moles of CCl4 = 95.64 grams / 154g/mol = 0.62104 mol

Step 7: Calculate total number of moles

Total number of moles = moles benzene + moles CCl4

0.45059 moles + 0.62104 moles = 1.07163 mol

Step 8: Calculate mole fraction benzene and CCl4

Mole fraction = moles benzene / total moles

Mole fraction of benzene = 0.45059 / 1.07163 = 0.4205

Mole fraction of CCl4 = 0.62104 / 1.07163 = 0.5795

Step 9: Calculate partial pressure

Partial pressure of benzene = 0.4205 * 74.61 = 31.37 mmHg

Partial pressure of CCl4 = 0.5795 * 91.32 = 52.92 mmHg

Total vapor pressure = 31.37 + 52.92 = 84.29 mmHg

The total vapor pressure is 84.29 mmHg

7 0

3 years ago

The radius of a lithium atom is 130 picometers, and the radius of a fluorine atom is 60 picometers. The radius of a lithium ion,

natali 33 [55]

Answer:

A positive ions is always smaller than the corresponding atom.

A negative ion is always larger than the corresponding atom.

Explanation:

The reason for this is that, when a positive ion is formed, a full shell is usually removed with its electrons thereby reducing the size of the electron cloud and decreasing the size of the electron cloud.

A negative ion is formed by addition of more electrons to the electron cloud hence it spreads out. Interelectronic repulsion accounts for the larger size of the negative ion.

3 0

3 years ago

Write a mechanism for the esterification of propanoic acid with 18O-labeled ethanol. Show clearly the fate of the 18O label. (b)

tatuchka [14]

Answer:

See explanation and images attached

Explanation:

a) In the mechanism for the acid catalysed esterification of propanoic acid using ethanol, we can see that the first step is the protonation of the acid followed by nucleophillic attack of the alcohol. Loss of water and consequent deprotonation regenerates the acid catalyst. We can see the fate of the 18O labelled ethanol in the mechanism shown.

b) In the second mechanism, an unnamed ester is hydrolysed using an acid catalyst. The attack of the acid and subsequent nucleophillic attack of water labelled with 18O leads to the incorporation of this 18O into the product acid as shown in the mechanism attached to this answer.

5 0

3 years ago

Why should scientists control most possible variables in their experiments?

irina [24]

Scientists should control most possible variables in experiments to get the most valid and correct data. If many variables are included in experiments it is more difficult to interpret what is causing a different outcome.

8 0

3 years ago