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2 years ago

5. How much heat (in calories) is absorbed by a reaction when

Chemistry

1 answer:

Wewaii [24]2 years ago

7 0

Answer:

1.2 × 10⁴ cal

Explanation:

Given data

Mass of water (m): 300 g

Initial temperature: 80 °C

Final temperature: 40°C

We can calculate the heat released by the water ( $Q_w$ ) when it cools using the following expression.

$Q_w = c \times m \times (T_f - T_i)$

where

c is the specific heat capacity of water (1 cal/g.°C)

$Q_w = \frac{1cal}{g.\°C} \times 300g \times (40\°C - 80\°C) = -1.2 \times 10^{4} cal$

According to the law of conservation of energy, the sum of the heat released by the water ( $Q_w$ ) and the heat absorbed by the reaction ( $Q_r$ ) is zero.

$Q_w + Q_r = 0\\Q_r = -Q_w = 1.2 \times 10^{4} cal$

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Consider 10.0 g of helium gas (He) in a rigid steel container. If you add 10.0 g of neon gas (Ne) to this container, which of th

Norma-Jean [14]

Answer: (e) The pressure in the container increases but does not double.

Explanation:

To solve this, we need to first remember our gas law, Boyle's law states that the pressure and volume of a gas have an inverse relationship. That is, If volume increases, then pressure decreases and vice versa, when temperature is held constant. Therefore, increasing the volume in this case does not double the pressure owning to out gas law, but an increase in pressure would be noticed if temperature is constant

6 0

3 years ago

How many kilograms of a fertilizer are made of pure P2O5 would be required to supply 1.69 kilogram of phosphorus to the soil?

Alekssandra [29.7K]

Answer:

3.89 kg P2O5 must be used to supply 1.69 kg Phosphorus to the soil.

Explanation:

The molecular mass of P2O5 is

P2 = 2* 31 = 62

O5 = 5 * 16 = 80

Molecular Mass = 142

Set up a Proportion

142 grams P2O5 supplies 62 grams of phosphorus

x kg P2O5 supplies 1.69 kg of phosphorus

Though this might be a bit anti intuitive, you don't have to convert the units for this question. The ratio is all that is important.

142/x = 62/1.69 Cross multiply

142 * 1.69 = 62x combine the left

239.98 = 62x Divide by 62

239.98/62 = x

3.89 kg of P2O5 must be used.

3 0

3 years ago

The volume of air in a person’s lungs is 615 mL at a pressure of 760. mmHg. Inhalation occurs as the pressure in the lungs drops

chubhunter [2.5K]

Answer: The final volume of lungs is 621.5 mL

Explanation:

To calculate the new volume, we use the equation given by Boyle's law. This law states that pressure is inversely proportional to the volume of the gas at constant temperature.

The equation given by this law is:

$P_1V_1=P_2V_2$

where,

$P_1\text{ and }V_1$ are initial pressure and volume.

$P_2\text{ and }V_2$ are final pressure and volume.

We are given:

$P_1=760mmHg\\V_1=615mL\\P_2=752mmHg\\V_2=?mL$

Putting values in above equation, we get:

$760mmHg\times 615mL=752mmHg\times V_2\\\\V_2=\frac{760\times 615}{752}=621.5mL$

Hence, the final volume of lungs is 621.5 mL

8 0

3 years ago

How do the Carnivorous plants survive without soil?

Mkey [24]

Answer:

Carnivorous plants are easy to grow, if you follow a few, simple rules.

Wet all of the time.
Mineral-free water.
Mineral-free soil.
Lots of light.

Wet all of the time.
Carnivorous plants are native to bogs and similar nutrient-poor habitats. As a consequence, the plants live in conditions that are constantly damp. To grow healthy carnivorous plants, it is important to duplicate their habitat as closely as possible. Keep the soil wet or at least damp all of the time. The easiest way to do this is use the tray method. Set the pots in a tray or saucer, and keep water in it at all times. Pitcher plants can grow in soggy soil with the water level in the saucer as deep as 1/2 the pot, but most carnivorous plants prefer damp to wet soil, so keep the water at about 1/4 inch and refill as soon as it is nearly gone. Water from below, by adding water to the tray, rather than watering the plant. This will avoid washing away the sticky muscilage of the sundews and butterworts and keep from closing the flytraps with a false alarm.

Mineral-free water.
Always use mineral-free water with your carnivorous plants, such as rainwater or distilled water. Try keeping a bucket near the downspout to collect rainwater. Distilled water can be purchased at the grocery store, but avoid bottled drinking water. There are simply too many minerals in it. The condensation line from an air conditioner or heat pump is another source of mineral-free water. Reverse-osmosis water is fine to use. Carnivorous plants grow in nutrient poor soils. The minerals from tap water can “over-fertilize” and “burn out” the plants. In a pinch, tap water will work for a short while, but flush out the minerals with generous portions of rainwater, when it is available.

Mineral-free soil.
The nutrient poor soils to which the carnivorous plants have adapted are often rich in peat and sand. This can be duplicated with a soil mixture of sphagnum peat moss and horticultural sand. Be sure to check the peat label for sphagnum moss. Other types will not work well. The sand should be clean and washed. Play box sand is great, and so is horticultural sand. Avoid “contractor’s sand” which will contain fine dust, silt, clay and other minerals. Never use beach sand or limestone based sand. The salt content will harm the plants. The ratio of the mix is not critical, 1 part peat with 1 part sand works well for most carnivorous plants. Flytraps prefer a bit more sand, and nepenthes prefer much more peat. Use plastic pots, as terra cotta pots will leach out minerals over time and stress your plants.

Explanation:

Kayo na Po bahala magpaigsi

5 0

3 years ago

A Rectangular Prism has a height of 4cm, a width of 5cm, a length of 1.2 cm, and a mass of 85,000 g. What is it's density?

wolverine [178]

Answer:

The answer is D.

Explanation:

Volume (V) = l x w x h

V = 4 x 5 x 1.2

V = 20 x 1.2

V = 24

Density = Mass/Volume or D = M/V

D = 85,000/24

D = 3541.66666666

4 0

3 years ago