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IRINA_888 [86]
3 years ago
6

Heat transfer by electromagnetic waves.

Chemistry
1 answer:
Bas_tet [7]3 years ago
5 0

Answer:

heat transfer by thermal energy

Explanation:cause thermal is hot air so heat transfer by thermal

You might be interested in
2. An oral rinse solution of
Mars2501 [29]

Answer:

Fluoride Toothpaste

Form

Concentrations of fluoride in toothpaste sold in the United States range from 1,000–1,500 ppm.

Use

Most people report brushing their teeth at least once per day, but more frequent use can offer additional protection. Fluoride in toothpaste is taken up directly by the dental plaque and demineralized enamel and also increases the concentration of fluoride in saliva.

Availability

Fluoride toothpaste is available over-the-counter and makes up more than 95% of toothpaste sales in the United States.

Recommendations

For most people (children, adolescents, and adults) brushing at least twice a day with a fluoride toothpaste—when you get up in the morning and before going to bed—is recommended.

Advice for Parents

For children aged 6 years and younger, some simple recommendations are advised to reduce the risk of dental fluorosis.

Supervise brushing to discourage swallowing toothpaste.

Place only a small pea-size amount of fluoride toothpaste on your child’s toothbrush.

For children younger than 2, consult first with your doctor or dentist regarding the use of fluoride toothpaste..

Learn more about oral health care for children.

Fluoride Mouth Rinse

Form

Fluoride mouth rinse is a concentrated solution intended for daily or weekly use. The most common fluoride compound used in mouth rinse is sodium fluoride. Over-the-counter solutions of 0.05% sodium fluoride (230 ppm fluoride) for daily rinsing are available for use by persons older than 6 years of age. Solutions of 0.20% sodium fluoride (920 ppm fluoride) are used in supervised, school-based weekly rinsing programs. Other concentrations also are available.

Use

Rinses are used daily or weekly for a prescribed amount of time. The fluoride from mouth rinse is retained in dental plaque and saliva to help prevent tooth decay.

Availability

Mouth rinses intended for home use can be purchased over-the-counter. Higher strength mouth rinses for those at high risk of tooth decay must be prescribed by a dentist or physician.

Recommendations

For children younger than 6, consult first with your doctor or dentist regarding the use of mouth rinse because dental fluorosis could occur if such mouth rinses are repeatedly swallowed. Because fluoride mouth rinse has resulted in only limited reductions in tooth decay among schoolchildren, especially as their exposure to other sources of fluoride has increased, its use should be targeted to individuals or groups at high risk for decay.

Fluoride Supplements

Form

Tablets, lozenges, or liquids (including fluoride-vitamin preparations) are available. Most supplements contain sodium fluoride as the active ingredient. Tablets and lozenges are manufactured with 1.0, 0.5, or 0.25 mg fluoride.

Use

Fluoride supplements can be prescribed for children at high risk for tooth decay and whose primary drinking water has a low fluoride concentration. To maximize the topical effect of fluoride, tablets and lozenges are intended to be chewed or sucked for 1–2 minutes before being swallowed.

Availability

All fluoride supplements must be prescribed by a dentist or physician.

Recommendations

For children aged less than 6 years, the dentist, physician, or other health care provider should weigh the risk for tooth decay without fluoride supplements, the decay prevention offered by supplements, and the potential for dental fluorosis. Consideration of the child’s other sources of fluoride, especially drinking water, is essential in determining this balance. Parents and caregivers should be informed of both the benefit of protection against tooth decay and the possibility of dental fluorosis.

Fluoride Gel and Foam

Form

Fluoride gel is often formulated to be highly acidic (pH of approximately 3.0). Products available in the United States include gel of acidulated phosphate fluoride (1.23% [12,300 ppm] fluoride), gel or foam of sodium fluoride (0.9% [9,040 ppm] fluoride), and self-applied (i.e., home use) gel of sodium fluoride (0.5% [5,000 ppm] fluoride) or stannous fluoride (0.15% [1,000 ppm] fluoride).

Use

In a dental office, fluoride gel is applied for 1–4 minutes. Home use follows instructions provided on the prescription.

Availability

Most fluoride gel and foam applications are delivered in a dental office by a dental professional. These higher strength products, if used in the home, must be prescribed by a dentist or physician.

Recommendations

Because these applications are relatively infrequent, generally at 3 to 12–month intervals, fluoride gel poses little risk for dental fluorosis, even among patients younger than 6 years of age. Routine use of professionally applied fluoride gel or foam likely provides little benefit to persons not at high risk for tooth decay, especially those who drink fluoridated water and brush daily with fluoride toothpaste.

Explanation:

4 0
4 years ago
At a certain position in a piping system, a solution with a specific gravity of 1.50 passes through an 8-cm pipe with an average
soldier1979 [14.2K]

Answer:

\Delta p=-2.60bar\\ \\\Delta p=-0.260MPa

Explanation:

Hello,

In this case, by using the Bernoulli equation:

p_1+\frac{1}{2}\rho v^2_1+\rho gh_1= p_2+\frac{1}{2}\rho v^2_2+\rho gh_2+\rho h_L

Whereas h_L accounts for the heat loss, so we can compute the change of pressure by:

p_1 +\frac{1}{2}\rho v^2_1+\rho gh_1= p_2+\frac{1}{2}\rho v^2_2+\rho gh_2+\rho h_L\\\\p_2-p_1=\frac{1}{2}\rho v^2_1+\rho gh_1-\frac{1}{2}\rho v^2_2-\rho gh_2-\rho h_L\\\\\Delta p=\rho *[\frac{1}{2}(v_1^2-v_2^2)+g(h_1-h_2)-h_L ]

Thus, we must first compute the velocity inside the 5-cm section by using the continuity equation:

v_2=v_1\frac{A_1}{A_2}=v_1*(\frac{\pi d_1^2/4}{\pi d_2^2/4} ) \\\\v_2=1.2m/s*\frac{8cm}{5cm}=1.92m/s

It means that the change in pressure in Pa turns out (density is 1500 kg/m³ given the specific gravity of the fluid):

\Delta p=1500\frac{kg}{m^3}  *[\frac{1}{2}((1.2\frac{m}{s})^2-(1.92\frac{m}{s})^2)+9.8m/s^2(0m-15.0m)-25\frac{m^2}{s^2}  ]\\\\\Delta p=1500\frac{kg}{m^3}*(-1.1232\frac{m^2}{s^2} -147\frac{m^2}{s^2} -25\frac{m^2}{s^2} )\\\\\Delta p=-259684.8Pa

Therefore, the change in pressure in bar and MPa turns out:

\Delta p=-259684.8Pa*\frac{1bar}{1x10^5Pa}=-2.60bar\\ \\\Delta p=-259684.8Pa*\frac{1MPa}{1x10^6Pa}=-0.260MPa

Such negative sign means that the pressure at the 5-cm section is lower than the pressure at the 8-cm section.

Best regards.

6 0
3 years ago
How many moles of Ag are in 43.1 grams of Ag2O<br><br><br><br><br><br><br>​
Ivahew [28]

Answer:

0.372 mol (corr. to 3 sig. fig.)

Explanation:

no. of mole of Ag₂O

= mass of Ag₂O ÷ relative atomic mass of Ag₂O

= 43.1 ÷ ( 107.9 × 2 + 16 )

≈ 0.185936151 mol

∵ Ratio of Ag:Ag₂O = 2:1

∴ no. of mole of Ag

= no. of mole of Ag₂O × 2

≈ 0.371872303 mol

= 0.372 mol (corr. to 3 sig. fig.)

3 0
3 years ago
Joe tries to neutralize 125mL of 2.0 M HCL with 175mL of 1.0M NaOH. will the neutralization reaction be completed? If not what i
Lemur [1.5K]

Answer:

1) The neutralization reaction will mot be completed.

2) pH = 0.6.

Explanation:

<em>1) Will the neutralization reaction be completed?</em>

For the neutralization reaction be completed; The no. of millimoles of the acid must be equal the no. of millimoles of the base.

The no. of millimoles of 125 mL of 2.0 M HCl = MV = (2.0 M)(125.0 mL) = 250.0 mmol.

The no. of millmoles of 175 mL of 1.0 M NaOH = MV = (1.0 M)(175.0 mL) = 175.0 mmol.

∴ HCl will be in excess.

∴ The neutralization reaction will mot be completed.

<em>2) If not what is the pH of the final solution?</em>

[H⁺] =[ (MV)HCl - (MV)NaOH]/V total = (250.0 mmol - 175.0 mmol) / (300.0 mL) = 0.25 M.

∵ pH = - log[H⁺]

<em>∴  pH =</em> - log(0.25) =<em> 0.6.</em>

4 0
3 years ago
A chemist set up a synthesis of phosphorus trichloride by reacting 12.0 grams of phosphorus with 35.0 grams of Cl2. 42.4 grams o
babunello [35]

Answer:

sorry i do not know

Explanation:

i do not know the answer you are asking sorry i was never really good in maths anyway

5 0
3 years ago
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