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2 years ago

14

List 3 countries known to have poor water quality.

1 answer:

mr_godi [17]2 years ago

7 0

Answer

Ethiopia, Niger, Chad

Exlination-

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For each metal complex give the coordination number for the metal species. m(nh34cl2

tankabanditka [31]

The coordination number is 6. The outer Cl- ion isn't included, so you count 4 x NH3 and 2 x Cl- are within Co's coordination sphere.

8 0

2 years ago

The black, granular material that fills a dry cell in a common flashlight (between the carbon rod and the zinc shell) is mangane

mestny [16]

Answer: c. +4

Explanation:

For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.

$Mn:25:1s^22s^22p^63s^23p^64s^23d^{5}$

$Mn^{4+}:21:1s^22s^22p^63s^23p^63d^1$

$O:8:1s^22s^22p^4$

$O^{2-}:10:1s^22s^22p^6$

Here manganese is having an oxidation state of +4 called as cation and oxygen forms an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged to give $Mn_2O_4$ which written in simplest whole number ratios to give neutral $MnO_2$

7 0

2 years ago

Determine which equations you would use to solve the following problem: Calculate the amount of heat needed to change 20.0 g of

Inessa [10]

Answer:

Q = 4019.4 J

Explanation:

Given data:

Mass of ice = 20.0 g

Initial temperature = -10°C

Final temperature = 89.0°C

Amount of heat required = ?

Solution:

specific heat capacity of ice is 2.03 J/g.°C

Formula:

Q = m.c. ΔT

Q = amount of heat absorbed or released

m = mass of given substance

c = specific heat capacity of substance

ΔT = change in temperature

ΔT = T2 - T1

ΔT = 89.0°C - (-10°C)

ΔT = 99°C

Q = 20.0 g ×2.03 J/g.°C × 99°C

Q = 4019.4 J

3 0

2 years ago

In what situations are van der waals forces the most significant

viktelen [127]

Its most significant when all other forces are absent

7 0

2 years ago

Ethanol (c2h5oh) melts at -114Â°c. the enthalpy of fusion is 5.02 kj/mol. the specific heats of solid and liquid ethanol are 0.9

Nimfa-mama [501]

Answer: 4.18925 kJ heat is needed to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -50°C.

Explanation:

Temperature of Solid $C_2H_5OH=-135^oC=138 K(0^oC=273K)$

Melting temperature of Solid $C_2H_5OH=114^oC=159 K$

Temperature of liquid $C_2H_5OH=-50^oC=223K$

Specific heats of solid ethanol = 0.97 J/gK

Specific heats of liquid ethanol = 2.3 J/gK

Heat required to melt the the 25 g solid $C_2H_5OH$ at 159 K

$\Delta T_1$ = 159 K - 138 K = 21 K

$Q_1=mc\Delta T= 25\times 0.97J/gK\times 21 K=509.25 J$

Heat required to melt and raise the temperature of $C_2H_5OH$ upto 223 K

$\Delta T_2$ = 223 K - 159 K = 64 K

$Q_2=mc\Delta T= 25\times 2.3J/gK\times 64 K=3680 J$

Total heat to convert solid ethanol to liquid ethanol at given temperature :

$Q_1+Q_2=509.25 J+3680 J=4189.25 J=4.18925 kJ$ (1kJ=1000J)

Hence, 4.18925 kJ of heat will be required to convert 25.0 g of solid ethanol at -135 °C to liquid ethanol at -50°C.

6 0

2 years ago