What change of state occurs during vaporization? liquid to gas gas to liquid solid to liquid liquid to solid

How many milliliters of water at 25.0°C with a density of 0.997 g/mL must be mixed with 162 mL of coffee at 94.6°C so that the r

Andre45 [30]

Answer:

The volume of water is 139 mL.

Explanation:

Due to the Law of conservation of energy, the heat lost by coffee is equal to the heat gained by the water, that is, the sum of heats is equal to zero.

$Q_{coffee} + Q_{water} = 0\\Q_{coffee} = - Q_{water}$

The heat (Q) can be calculated using the following expression:

$Q=c \times m \times \Delta T$

where,

c is the specific heat of each substance

m is the mass of each substance

ΔT is the difference in temperature for each substance

The mass of coffee is:

$162mL.\frac{0.997g}{mL} = 162g$

Then,

$Q_{coffee} = - Q_{water}\\c_{c} \times m_{c} \times \Delta T_{c} = -c_{w} \times m_{w} \times \Delta T_{w}\\m_{c} \times \Delta T_{c} = -m_{w} \times \Delta T_{w}\\m_{w} = \frac{m_{c} \times \Delta T_{c}}{-\Delta T_{w}} \\m_{w}=\frac{162g \times (62.5 \°C - 94.6 \°C ) }{-(62.5 \°C - 25.0 \°C)} \\m_{w} = 139 g$

The volume of water is:

$139g.\frac{1mL}{0.997g} =139mL$

7 0

4 years ago

Below is a circuit schematic of sources and resistors (Figure 3). VS = 10V , R1 = 100Ω, R2 = 50Ω, R3 = 25Ω, IS = 2A. Calculate t

lorasvet [3.4K]

Answer:

$V_3\approx 4.28\,\,V$

$I_1=0.0572\,\,amps$

$I_3\approx 0.171\,\,amps$

Explanation:

Notice that this is a circuit with resistors R1 and R2 in parallel, connected to resistor R3 in series. It is what is called a parallel-series combination.

So we first find the equivalent resistance for the two resistors in parallel:

$\frac{1}{Re}= \frac{1}{R1}+\frac{1}{R2}\\\frac{1}{Re}= \frac{1}{100}+\frac{1}{50}\\\frac{1}{Re}= \frac{3}{100}\\Re=\frac{100}{3} \,\,\Omega$

By knowing this, we can estimate the total current through the circuit,:

$Vs=I\,*\,(\frac{100}{3} +25)\\10=I\,*\,\frac{175}{3} \\I=\frac{30}{175} \,amps$

So approximately 0.17 amps

and therefore, we can estimate the voltage drop (V3) in R3 uisng Ohm's law:

$V_3=\frac{30}{175} *\,25=\frac{30}{7} \approx 4.28\,\,V$

So now we know that the potential drop across the parellel resistors must be:

10 V - 4.28 V = 5.72 V

and with this info, we can calculate the current through R1 using Ohm's Law:

$I_1=\frac{V_1}{R_1} =\frac{5.72}{100} =0.0572\,\,amps$

4 0

4 years ago

Define static electricity and ohms law

iVinArrow [24]

Answer:

Static electricity : is a familiar electric phenomenon in which charged particles are transferred from one body to another

Ohm's law : states that the voltage or potential difference between two points is directly proportional to the current or electricity passing through the resistance

6 0

3 years ago

A student measures the pH of a solution to be 6.8. Which should the student add if she wants to decrease the pH of the solution?

zloy xaker [14]

The neutral pH is 7. Less than 7 indicates an acid and more than 7 indicates a base (up to 14).
 NaCl - it's a salt (we can't measure the pH)
H2O - it can be an acid but also a base (the pH it is almost neutral,meaning close to 7 )
HF - it is a strong acid
 KOH - it is a strong base (pH=14)

↓

He needs to use HF (Hydrogen fluoride) to decrease the pH.

7 0

3 years ago

Read 2 more answers

How much work is done (by a battery, generator, or some other source of potential difference) in moving Avogadro's number of ele

luda_lava [24]

Answer:

W = 1.5 x 10⁶ J = 1.5 MJ

Explanation:

First, we calculate the potential difference between the given 2 points. So, we have:

V₁ = Electric Potential at Initial Position = 6.7 V

V₂ = Electric Potential at Final Position = - 8.9 V

Therefore,

ΔV = Potential Difference = V₂ - V₁ = -8.9 V - 6.7 V = - 15.6 V

Since, we use magnitude in calculation only. Therefore,

ΔV = 15.6 V

Now, we calculate total charge:

Total Charge = q = (No. of Electrons)(Charge on 1 Electron)

where,

No. of Electrons = Avagadro's No. = 6.022 x 10²³

Charge on 1 electron = 1.6 x 10⁻¹⁹ C

Therefore,

q = (6.022 x 10²³)(1.6 x 10⁻¹⁹ C)

q = 96352 C

Now, from the definition of potential difference, we know that it is equal to the worked done on a unit charge moving it between the two points of different potentials:

ΔV = W/q

W = (ΔV )(q)

where,

W = work done = ?

W = (15.6 V)(96352 C)

W = 1.5 x 10⁶ J = 1.5 MJ

7 0

3 years ago